I'm not crazy about strategy RPGs which is a cat on it's own, but I do know of a few REALLY good games he would like.  FFXII for the DS that just came out is perfect since it's a combination of the two.  Not only that but FF games in general are very good.

One of my personal favs is Puzzle Quest.  My review on this game actually got on Nintendos community home page back in the days of Nsider XD.  Quick summary is that it's an RPG with a bejeweled like battle system.  The story changes depending on the choices you make.  You build your character up and forge new weapons, capture towns, gain friends and abilities.  It does take some strategy to play too since you want to become skilled in combat.  There are also capturing of enemies and trying to learn their abilities.  Endless game play too and just one play through will take about 100 hours. 

I know he likes some of the games in the FF series, so maybe I will look into those more. I took a look at the Final Fantasy series before, but so many of them are remakes and such, I get confuzzled.

I actually have PuzzleQuest. Awesome game, but I think it's a little too puzzle-y for my boyfriend. Besides, he could always play my copy. I also have Elite Beat Agents. That's an awesome game too.

Thanks for the suggestions so far.

I'm sure he would like the Golden Sun series. In fact, I think he has one of them for the GBA. However, I do want to get him a DS game to go with his new DS.

I have Tetris DS ... I'm looking to get something a bit more RPG-ish for him.

I'm not too big on "Strategy/RPG" sort of games, but, one that sort of fits that which I've enjoyed somewhat is Age of Empires: The Age of Kings.
I'd never played any of the Age of Empires games for PC, but, got this game when it was on sale at Electronics Boutique a bit back, and, it's been an interesting game. Again though, I'm not really an expert on the genre, it's just the only one that's along those lines that I have.

As far as just regular RPGs go (not sure if he'd be interested in those), Magical Starsign is a great game, and I'd definitely recommend if he's interested in a regular, non-strategy, RPG.
It's by Brownie Brown, which is made up of a bunch of people who had worked on Secret of Mana for SNES (and have as this group done Sword of Mana for GBA which is interesting, and Heroes of Mana which I haven't had a chance to play), and prior to Magical Starsign they also worked on Mother 3 for GBA (which, despite being in Japanese, I love). Just figured I'd mention that in case it would be of interest.

you can always pick up Mario and Luigi: Partners in Time.
its an awesome game, RPG (of course) with an intutitive easy-to-pick-up-hard-to-master battle system...
there is also the GBA game that game before it :Mario and Luigi Superstar Saga i think it was called...
they both have incredibly funny dialogue, though not a lot of replay value, but its a good buy nonetheless...

there have been one or two Tactic rpgs on DS, though their name escapes me right now...
i do remember one was a remake and it got decent scores.. nothing outstanding but decent enough to stad on its own...
i forget...

Nifty. Yeah, if he's interested in regular RPGs as well, as I said, I would highly recommend Magical Starsign, as it's a wonderful game.
It makes some convenient use of the DS's features, but, the important thing is that, at its core, it's a great RPG, and one that I enjoyed very much.

I actually ended up picking up Heroes of Mana. I couldn't find Magical Starsign, and I really didn't feel like driving all over the place to find it since I saw Heroes of Mana sitting there.

We actually already exchanged gifts already since my cousin's side of the family had their little get together yesterday. Of course he loves the DS, and he said he can't wait to play Heroes of Mana. Looks like it was a good pick. So thanks everyone for the suggestions.