If you're in the $14-20 range, Willm or Trimbach (from Alsace) or Dr. Frank (Finger Lakes, NY).
If you want to go above that, get something German. Ask at a wine shop. Good German Riesling is impossible to figure out if you don't know what you're doing.
If you want to go below that, Hugel (Alsace) or Kung Fu Girl (Washington state). Yes, Kung Fu Girl sounds kitschy and it's available on every bar happy hour menu, but it's actually pretty good entry-level Riesling.

Loosen is a great name in German riesling, and has joint ventures in other Riesling areas around the world. Dr. Loosen is from Washington state, I think, and is kind of entry-level. It's not bad, but I find it a little on the round, sweet side. That's not a bad thing for a Riesling, but I like them a little bit leaner.

Depends, do they like dry rieslings? Sweet? Ice wine?

Also there are different regions here in N America with Finger Lakes, Niagara Ontario, Washington, and some other areas, though none as common as those three. There's also the difference between Alsatian and German. I personally think German is the pinnacle of riesling, with incredible variety as well.

Dee Vine Wines in San Francisco is the best retailer of German wines.

Dr. Loosen

I'd just go to Total Wine and ask them for help. They know their stuff.

Go to a good wine shop - one of those where the shopkeepers actually have an idea about the wine and check there. I don't know where you are, but the wine shop in bethesda - beside the crab place is good and has some great riesling. I like rieslings a lot, and enjoy most of the german ones that i buy.

Kung Fu Girl. It's slightly dry and delicious!

Any suggestions on good Rielsings for a thank you gift? The person I am gifting to only likes Riesling. Also, any recommendations on a gift basket/wine delivery service where we can pick the wines?