Playdough? They have some really fun sets.

All my boys (husband and my brothers included) LOVE Air Hogs. They are super cool tiny remote control helicopters that you can fly in the house. Even my 4 year old was able to master flying them.

Magna-tiles, beyblades, ninjagos, hot wheels cars

Legos seem to be something that just click at certain times for some kids. DS received some Lego sets for his 5th birthday, and they sat around unopened for a couple months. I encouraged him to pick a set to put together one day, he did, and now he is a Lego freak and wants nothing but Legos for Christmas. I think something clicked in understanding the directions and feeling like he could do it himself. That's a long way of saying your DS still may get into Legos so you could still get him a few sets. My DS was otherwise very similar to yours, was never really into anything in particular except office supplies, workbooks, writing, etc.

My son plays a lot with his uglydolls--great for imaginative play. He's also into playmobil. One favorite game is No Stress Chess.

Your son would love a Nintendo Wii. They are fun for the whole family. My nearly 7 year old is never still while he is playing, he is always hopping all over the place. He also loves it when my husband and I play with him.

Magnadoodle
Big blocks
Art stuff

OP here -- He has been into games. Candyland was a big hit for a while. Keep the game ideas coming!
I haven't decided whether or not to get into electronics, seems another thing to have to say no too (already has a bit of tv, does abcmouse.com and is occasionally allowed to do apps on my phone).
Thanks!

My son won an easel and uses it a lot. I think it is made by Melissa and Doug. Has a white board on one side and a blackboard on the other, with a paper feed in the middle and space for paints and chalk. We've used it for 4 years now and my son is 6.5 .
Magna doodle is another big one for my artistic son.

costumes to play dress up, magna tiles, books, plastic dinosaurs or animals...these are some of our favorites.

(I would hold off on nintendo and I really don't like leap frog--the screen is small and barely readable)

Sadly, mine is into electronics. When they are taken away or his time limit is done - he plays soccer outside or with race tracks still inside. He is losing interest in "toys" and would much rather do crafts or workbooks as well. Any type of project is fun for him.

Ditto games. Guess who, connect 4. Spot it.

Not really what you're looking for, but my son likes games - any game that is age appropriate really. Zingo is the latest, but there are tons of others that he plays.

Are you against electronics? Nintendo ds, and you could buy educational games for it. Leapfrog? Or the usual iPad... What five year old doesn't have one?

Beyblade.

My son's 5th B'day is coming up and the grandparents are asking for gift ideas. My DS mainly does crafts -- writing, cutting, workbooks -- which is great but I'd also like to have him get into other toys that keep him busy and encourage imagination. He's shown very little interest in Legos, got bored with trains after a few months, has never been into toy cars or trucks. As I'm writing this, I'm really not sure what he does all day...
Anyone else have a son like this? Any suggestions of toys he might get into?
Thanks!