The wife and I want to start playing more games together, and this has lead us on a hunt for some good board/card/dice/whatever games that work well with 2 people. The problem is, many of the games that say "From 2-6 players" are horrendous for 2 players due to reliance on diplomacy, duplicity or other factors.

Any suggestions for good 2 player games that can be played in an evening after the 4 year old has decided he wants to stop bothering us and go to sleep?

I'll always recommend Arkham Horror.

But you can also look into Last Night On Earth, which was quite a bit of fun.

I enjoy Carcassonne as a two-player game. You actually have to plan much more strategically because you control a much larger number of tile placements compared to larger games.

Look up Yomi and Puzzle Strike. You can actually play them online to get a feel for the games.

Fairly simple rules (enough that they go on one folded sheet of paper) and a ton of depth to the game play.

Puzzle Strike is a Dominion like Puzzle Fighter game that uses chips instead of cards. A lot of fun and probably best with 2 people

Yomi is a fighting game card game that uses a fairly simple paper-scissors-rock style with Attacks-Throws-Blocks and combos. A lot of fun and fairly quick. Decent amount of strategy there.

Battlelore.
Battlelore.
A thousand times Battlelore.

Board Game Geek page

Well, if you're into that type of game. I think it's fantastic and my friend and I have had hundreds of hours of fun with it. We've played through the campaign book a couple times and played a few scenarios we downloaded online. We liked that you could tailor the game to whatever level of complexity you wanted for the session.

Mr. Jack is a pretty fun game that is 2 player only.

Quick games:

Tsuro- This game is a LOT of fun for such a simple game. It is just as good with 2 players as 8 because both games have a different feel

Fluxx-find your preferred version

Travel Blokus/Blockus Dou



Longer Games:
Castle Ravenloft
I haven't done Arkham Horror with 2, but I can see it still being fun.

Fluxx is a good call; it's one of the few multiplayer card games that holds up with 2 players.

Arkham Horror works well with two people. The Wife and I have played it a number of times. There are two variants you can shoot for: almost guaranteed death and decent chance of success. If you play with one investigator each, the game is extremely challenging because you simply don't have enough of an action economy to do everything on the board. If you each double up with investigators, it's just like playing 4-player (i.e., the game is intended for this many investigators) but goes a little quicker if you're both familiar with the rules.

Pandemic works well with two, as does Forbidden Island. It's also OK in both of those to double-up on roles, so long as you make sure to use the four-player rules (which is pretty much automatic; those two are auto-balancing).

I've also enjoyed the Catan card game, which is currently sold under the title The Rivals for Catan.

Space Hulk: Death Angel is a great game for two. It's also a fun game for one.