People with a little fat on their thighs (most women) can wear the sensors there, although it's not FDA approved (lots of women do it). I have friends that wear them there, but it didn't work for me.
You can also try your butt- most people have good results there (including me).
The Dexcom CGM has a strong transmitter. It can definitely go through pants. The minimed CGM has a weaker transmitter, but it can go through all of my pants.
BTW, in the US, both Dexcom and Minimed came out with new CGMs in the last two years. Minimed now has the enlite sensors (same old tranmitter) vs the old sof-sensors, and Dexcom now has the G4 sensors vs the old 7+ sensors.
I have used all four CGMs I mentioned.