4 of us are going and are taking so long to decide we have lost the best choices. We need to make a decision in the morning. The only hotels available on our package are Luxor, Treasure Island, MGM Grand & Alladin. Which should we choose-best location, nicest hotel? Would it be worth it to pay about $400 extra to stay at the Venetian? Please help or our trip will be toast.

You might want to repost with Las Vegas (I'm assuming that's where you're headed) in the title. You'll get more help that way.

IMO no it wouldnt be worth $400 extra. As far as which to pick...my pick would be TI. Location Location. Alladin has a decent location as well but IMO isnt as nice as TI. MGM and Luxor would be fine if you dont plan on spending much time down th strip. If you do you will be walking ALOT or paying for transportation. Of those two however I would choose MGM due to its proximity to the monorail. So my order of preference is.
1. TI
2.Alladin
3. MGM
4. Luxor

I am mostly with panhandle on your choices except I would alter the top choice. Here is my recommendation including the NO to Venetian for $400 more.

1. Aladdin
2. TI
3. MGM and Luxor tied.

Whatever you choose, I hope your group has a great time and can come to decisions on entertainment, dinner, etc. before the sun rises the next day ;-)

If it's 4 of you in one room, take the Aladdin for the larger bathroom and separate toilet-closet. It's also the best location in my opinion.
Venetian for $400 more would depend on how long you are staying. $400 extra is too much to pay for 2 nights, but if it's $400 extra for a week, it's probably worth it for the spacious room.