I highly recommend the postal museum right by Union Station.

Be careful about cherry blossom tourist traffic. Double check your trip doesn't coincide with peak bloom.

If your 3-year-old is anything like mine, the Metro will totally be the highlight of the day. I'd head to American History's America On the Move exhibit, which features really locomotives, cars, and a streetcar that you can sit in with lights and sounds.

Then I'd go outside, maybe ride the carousel, run around on the mall, and eat lunch--either a picnic outside if it's nice, or one of the museum cafes (Natural History's is closed for renovation. American History's is fine for families, but American Indian has great food).

Then, I'd either do the Sesame Street planetarium show that someone else mentioned at Air and Space, OR the Insect Zoo at Natural History, and then go home. He'll probably fall asleep on Metro ride home

You don't need to plan it out that carefully, get on the train, got to one museum (American HIstory or Native American), run around on the mall, eat a snack/lunch, go home.

I would skip Air and Space. The kid section is normally really packed and it is hard for a kid to be able to use the kid friendly exhibits without being assertive. I love their stuff and we take DS but it was better when he was 5 and it was easier for him to be noticed by the older kids who are running from thing to thing.

But at 3 he would have been thrilled if we rode the metro from one end of the line to the next. Heck, at 6 the most exciting ride for him at Disney is the train. He really, really likes trains.

The Wegman's Wonderplace is very small and kind of underwhelming. I wouldn't seek it out for a special visit if you don't make it to the museums often. My son like the Batman car and the America on the Move exhibit in American History.

In Natural History, the bugs are definitely a highlight (skip the paid butterfly exhibit). Plus they are right next to the dinosaur bones. The Hall of Mammals is usually a hit as well. Q?rious is too advanced for a 3 year old, Q?rious Jr. would be better, but it's closed on Sunday and Monday.

If you are coming in on the red line, you could consider riding to Union Station and seeing the Postal Museum, which is great for a 3 year old. It's not on the mall, though, so I don't think that's what you are going for.

Don't try to do too much. Some of the museums on/near the Mall have kid play areas--the Building Museum (with times tickets), American History, American Indian, Natural History, etc. Look online to see if any of them have story times or events that your kid might like. Kids also often like American History (America on the Go has real cars/trucks/streetcars at eye-level) and Air and Space. Natural History's Hall of Mammals is also pretty kid-friendly.

Pick one or two museums to see. Don't try to cram too much into one morning.

The Natural History Museum has two spaces specifically for kids with hands on activities. The one for older kids in Q?rious. I’d check the website for location and hours for the other space. Lots to see in that museum but I’d see how long your child enjoys it. They do absorb information, although it can be hard to tell. Id ask questions about what they are seeing to help them connect.

https://www.si.edu/visit/kids has the highlights

If I were you, I'd do the Wegman's Wonderplace at American History, then a break/snack/lunch, and walk over to Natural History and see bugs.

If he is anything like my son at 3, the metro is all he is going to talk about. It didn't matter what else we did. It was all about the metro.

I would skip the Native American Museum and head to Natural History, the gems are cool and he will probably like the rooms with all the animals.

Don't try to do too much. It's very possible the metro ride will be the highlight of the day for him. One possible Itinerary:
-Ride metro to L'Enfant
-Go to Air and Space, watch free Sesame Street show in Planetarium 10:30-11 (def on Sundays, website says every day now?) and visit How Things Fly exhibit for hands on stuff
-Eat lunch at American Indian Cafeteria or McDonalds at 4th&C SW
-Visit kids area in American Indian museum
-Leave, because your 3 year old is now cooked. If he's still happy you can add the carousel.

I would recommend leaving the baby behind, since you have the option. It will be much more pleasant for you to enjoy the day with just your big kid.

I would plan for your 3 year old to be entertained inside a museum for no longer than one hour. Even if you try to go to different museums, the one hour limit holds. After that, he will want/need to run.

Yes I'd metro down at 9am. Most museums open around 10am (check for Sunday opening times). Walk around, then have a picnic or snack outside while he runs off some energy. Then I'd head back home for nap time.

A lot of museums offer family friendly programming , both the Smithsonians and non-Smithsonian. It’s worth it to see what’s available - for example, Hillwood does weekday family programming, and the Building Museum has a first-Saturday Family day thing with free or reduced admission, and a ton of activities.

You could always skip the museum and just take the metro to the Mall, have a picnic and ride the carousel if you’re concerned about navigating the crowds.

The DC metro is very manageable with a stroller and one or two kids. If you take your 2 month old, I would take the stroller and a carrier so you can have the option for both.

When you board the metro, get on the very front car as those are normally less crowded.

I would suggest packing a lunch and checking out any of the following: American Indian museum, American history museum, Building Museum (you pay to get in and pay for special exhibits though), sculpture gardens, carousel on the mall, gardens in back of the Castle.

I & DH plan to take my 3 year old active boy to dc museums in April by taking metro the first time. Any recommendations for fun, laid-back & kid-friendly dc museums itinerary with schedules? And, he still naps in the afternoon for 1.5-2 hours, but we have done that before without any naps(just more hyperactive). We are thinking to leave around 9am from home (closest metro is shady grove station), and leaves dc around 2pm, good or bad idea?

And, I will have a 2 months old as well, good or bad idea to bring her along in baby carrier? We have an option to leave her with grandparents at home, or have grandparents come with us altogether (with baby stroller or/and carrier) with metro? I can take baby stroller on metro, right?