Personally, I think a rogue does best by spreading his bonuses out over all the abilities.
Str: If you tumble, you need the strength to carry your equipment and still be at a light load.
Dex: Generally one of your top scores. Best way to a reasonable AC, and often gets combined with Finesse to improve your attack with the weapon you usually use. Lots of your skills are Dex based as well.
Con: Helps you survive when you occationally fail your save vs. the fireballs and such. You aren't going to be able to last long in melee, but it would be nice to last longer than the wizard or sorceror.
Int: Gives you a bonus to your core strength: Skill points. Take this pretty high to start, but in general pump other attributes as you level up. You don't get to add skill points for the levels you've already gained when your Int modifier is raised. On the other hand, when the Wizard is done with his Headband of Int+2 (because he got a better one), you should immediately ask for it. The earlier this stat is raised, the more useful it is. Don't forget to take your starting languages, so you can understant that giant who's lips you are trying to read.
Wis: This would be a dump stat, if only it didn't add to your Will save, Spot check, Listen check, and a few other key areas. Still, it is quite often the lowest ability.
Cha: Adds to a number of very important skills (Use Magic Device, Bluff, Diplomacy) that are just plain fun to use.
When using point buy, I generally figure out how high of attributes I would get by pumping all the abilities equally. Then I start moving points around to concentrate on Int, Dex, Con, Cha, Str, Wis.
I generally take tumble, so I figure out what Str score I would need for the equipment I plan to carry and work back from there.