the downtown is getting hipster'd up, there are a ton of little tech startups now and all the associated hipster doofus shit that comes along with it, like art stores, weird chi yoga infusion lifestyle centers, coffee shops, vegan restaurants etc etc. the owner of zappos has poured millions and millions into building up downtown vegas into a little san fran, austin, san diego, etc and its definitely getting closer (but still quite a ways). the grand is a new hotel there that is quite nice, and all the other hotels are pouring tons of money into remodeling and shit. it still feels a bit skeevy compared to the strip though.
that said the convention center will be a bitch to shlep to EVERY day, yeah maybe the taxi is only $20 but you will spend a ton of time in shitty traffic and sitting around waiting the last 2 blocks to get past the hordes of people walking in and out of the center. I suggest staying at the las vegas hilton (sorry just LVH now), its about 2 blocks from the convention center (and on the monorail) and after spending 6 hours on your feet walking around a convention center its really nice not having to waste 30-60 mins getting back to your hotel, plus you can monorail to the strip hotels easy. the rooms are ok, pretty old but I guess they are remodeling.
if you go downtown go to pizza rock, new place that is hands down the best pizza in vegas and most of the country