I just recieved Metroid Prime and so far its really amazing. Not just the shootem up parts either. Everything is voice acted pretty well and when your in your ship you control Samus' hand to push buttons and operate your radio and destination and stuff. Just tons of fun so far. (im only about 3 hours in right now). Also from my understanding there is a better ending if you collect a certain percentage of things throughout the game so that might be incentive for at least a little replay value.
If you dont mind Strategy RPGs then Fire Emblem is a really good choice too. Unless you played the Gamecube one and got sick of it cause there are a lot of similarities. I havnt finished it yet but if its like the Gamecube one itll have quite a few unlockables and secret characters and stuff so i think the replay value could be quite high if you like this kind of game.
I thought Trauma Center was a really solid game the first time through but didnt have much drive to replay that one at all.
I havnt played Zack and Wiki (yet) but from the gameplay footage ive seen it looks like a pretty solid game. Again i dont know about replay value but definately look into this one more if it really interests you. I know there are quite a few members on the site that have opened threads about this game so maybe check out one of the threads and PM a few people asking about it.
If you dont mind the presentation of Super Mario RPG (you didnt mention it so im assuming you havnt tried this one) it was really good. A decent length story mode with lots of variety to keep you interested (4 characters with different abilities and many many side quests). There is lots to do after you finish the game but its mostly either collecting items to complete sets of things or doing the 100 floor dungeons, so it can be pretty tedious if your not into that.
Guitar Hero III for the Wii was pretty sweet too. The online works really well and was a lot of fun so that was a huge replay factor for myself. If you like the track listing on the game youll probably enjoy it a lot.
Also since it sounds like you have some money to burn i would suggest picking up a Wii Points card or two. Tons of great games to download and more are always coming.
You can PM me too if you have any more specific questions about the games ive mentioned (except zack and wiki) or any other wii games because ive finished quite a lot of them.
