How do you calculate what to frequency to use in the Local oscillator for a 2.4Ghz Transciever
I'm not going to give an answer based on your requirement but instead explain a little about the 100MHz commercial FM broadcast band.

It generally ranges from 88 to 108 MHz (a 20 MHz span) and the Intermediate Frequency (IF) is chosen to be at 10.7 MHz (slightly higher than twice the range of 20 MHz). With an IF of 10.7 MHz the local oscillator (LO) can be 10.7MHz lower (or higher) than the signal to be received. 

For instance, if you wish to tune a radio station at 88 MHz then the LO will need to be 77.3 MHz (or 98.7MHz) and here's the subtlety....

A LO frequency of 98.7MHz could also "pull-in" a radio transmission that is transmitted at 109.4MHz and that is why the FM broadcast band is limited to 20MHz with an IF of slightly larger than half of this. Clearly nothing is transmitted at 109.4MHz that has the power of commercial radio hence, having an IF of 10.7 MHz is just enough to ensure full coverage without double reception.

So, the LO frequency depends on IF and IF depends on the band of frequencies you want to receive.

Regarding up-conversion and, dependent on what your modulating signal is, you might not use a LO and directly convert to your transmission frequency. A lot of radio receivers at 2.4 GHz directly down-convert without using a LO.