Leatherman Micra, and other small leathermans
Ka-bar mini dozier I think is 2.5in
Spyderco ladybug, manbug, bug, honeybee, grasshopper, and probably a few more (lots of bugs in the spyderco line)
Victorinox Class, Rally, Rambler, etc
And there are plenty of others but these are what I can think of off hand. Personally I wouldn't have much of an issue with any of those except mabey the smaller honeybee, bug, grasshopper but thats due to personal preference. I own the micra, rally, and full size ka-bar dozier hunter all of which are good knives. Personally I get the rambler and pair it up with something along the lines of the manbug or mini dozier as the rambler has a lot of small useful tools and combined with a bigger blade of the mini dozier or manbug and you be set. Blade on the micra is quite usable too, on the smaller Victorinox knives not so much in my opinion unless your doing small detailed work I just don't trust them and prefer something sturdier. Though thats personal preference.
EDITED IN:
Some full size swiss army knives have a 2.5in blade. Off hand they are the Victorinox recruit which I just measured and should be the cadet as well. If I am not mistaken pretty much any 84mm model should have a max blade length of 2.5in. Don't underestimate them they are great knives and I have never heard anyone say otherwise.
With that in mind I would probably get the Rambler, and pair it up with a Cadet, mini dozier, manbug. I like pairing up the smaller swiss army knives with a larger knife as it just fills in all the gaps nicely. And you still have a knife on you if you forget your primary knife but you have your keys (if you attach it to your keychain).