Indoor event lens

I was asked to shoot an indoor event for a company party. (not paid, but as a favor) Some of the pics they want are of the room and the lighting prior to start (probably need wider) Some will be of the people when the event starts - again wide and some portrait (2-3 people at a time) What lens would you recommend?

All depends on your budget.

Room = efs17-55IS for 50D or 24-70 for 5D/1D/1Ds
Use a flash like a 430EXII or 580EXII

Hall = 70-200 2.8IS (rent it if it's too expensive) on any eos camera.

EDIT: Wait, company party photographs as a favor-- rent or buy a 430EXII for the day and use your 28-135mm. it should be good enough. Learn to use the flash well =)

Normally I would say a 2.8 zoom or a couple of fast primes, but this is a free gig. Just use what you have at ISO 1600-3200 and run noise reduction on them. Resized for web or printed at normal sizes they will be fine.

Ask your office to rent you a flash (or buy one for you if they want) and since it is a free gig I too would use what you have, if you want to impress rent the 17-55 2.8 IS as well.

Are you buying the lens specifically for this or do you want something that is more multipurpose? Using flash?

Actually this is an excuse to pick up a new lens. Would want something that could see some day to day use as well - family pics, travel...

I would recommend the 17-55 IS, if you want a prime the 50 1.4

What is your budget? If the Canon is too pricey the Tamrons (17-50 or 28-75 both 2.8 ) are great bang for the buck.

Another vote for the 17-55, for what your talking about for the future this will be the perfect lens for you.

And another vote for the 17-55 IS!

ditto on 17-55IS

17-55 IS if you want an excuse to buy another lens.