I've got three sims, Ripmax, G2 and Cockpit Master. G2 is very realistic but can become quite dull after a while, ideal to practise particular manouvers and has tons of options, plus heli's of course. The Ripmax sim I probably use the most but is only sold in the UK at present, it's very nice to look at and is realistic if you use a tx (It's not at all the same program if you use a PC joystick), The scenery is much more varied and although the locations are not all traditional flying fields they are quite enjoyable, for instance you can try to land on an aircraft carrier, the castle site gives you a good idea of the location of the model relative to the ground. Look at www.rcsimulator.com
for more info. Plus it's a lot cheaper
I personally would not recommend Cockpit Master, to say I was disappointed is an understatement.