so all the single chip solutions i've ever looked into tend to have a very short range on their own.
many are intended to have additional RF amplifiers between them and the antenna.
if you need more than a few 10s of meters range you will probably need an amplified solution.
since time is an issue i recommend you look into pre-made RF modules. this will simplify the process greatly as they will have all the hard work of picking an RF chip, switch (if its a transceiver) and amp that work together providing you with a simple interface. (typically UART or SPI.)
some questions that will help narrow down the search:
one way (TX and RX) or 2 way (transceiver)?
indoor or out door?
what country are you in? (this will affect what bands you can transmit on.)
any other restrictions on frequency?
is there much other traffic on that band in your area?
after that, search through DigiKey for RF modules.
it's hard to get expected ranges for some of these modules but the manufacturers always specify the TX power out put and RX sensitivity level.
so if you find a datasheet that does have a published range, make a note of the power TX level, the RX sensitivity level and the frequency so you can get a ballpark idea for other modules.
i've some notes on using some transceiver modules here: http://sites.google.com/site/mrdunk/
but it's not really complete yet as i'm still getting a lot of interference from other 2.4GHz sources.