Haven't been in over three years, but in generally, Urumqi appeared to me, as a typical booming Chinese city, which I find interesting since I can be an econ/development nerd. I hear the Uyger quarter is very interesting, and that the city has a few other things to see and do that are noteable, besides natural resource/energy related stuff (the source of recent economic boom).

Around Urumqi (a 1-2 hour drive) is Turpan, which has a great mosque, and interesting vineyards with fascinating underground irrigation methods. On the way back you should be able to go to the Jiaohe ruins which are very interesting. A must do day trip.

There is also Tian Qi Lake, but I've never been. Here that although quite touristed in certain areas (isn't everything?), that it is stunning and tons of exploring to be had if you're one for the outdoors, or just want the experience for 1 or more nights.

To be honest though, I only wandered randomly for a few hours in Urumqi since I used it as a rest/recharge point. If you have time, and can push your trip into later April (rather than March), I would recommend that you travel into Xinjiang's other places. I went to Kashgar and spent 3 days there which was incredible. Be sure to try to catch the Sunday markets (regular and animal, latter is better), walk in around and about Id Kah mosque and its neighborhoods and drive out to Karikul Lake, amongst other things. While there is (or was then) a 50/50 split between Han Chinese and Uygers, the town had a very non-Chinese feel to it, which was fascinating. The streetside kebabs are fantastic, fresh and cheap. If you can speak some Mandarin (or even if you can't) it is worth sitting down for a meal/snack of kebabs, bread and unlimited tea with locals, whether off the street, or pretending to carpet shop. The locals are extremely friendly and engaging. Definite plus if you can speak Mandarin.

I do heat Hotan's market is better than that of Kashgar, but have not been able to visit (hope to sometime in the near future).

Also, there is an active currency market in Kashgar (or was) where all kinds of foreign currency notes are sold at near market prices (the vendors must follow rates closely). I'll pay anyone who can get an old style Iraqi or Afghan note the cost of the note, shipping and a premium. Sadly my "Saddam Dinar" and Aghan note were lost with my old wallet.