I've not had sex for several millennia now, but did a hell of a lot of it before. I'm pretty boring, certainly by what I gather to be contemporary standards! I think I'm quite good at it (leaving out kinks, which I'm very bad at) and fortunate in that it comes easily, iyswim.
I've only ever had marked orgasmic contractions while I've been 'sitting' on top. However, they didn't feel very orgasmic and, tellingly, my partners didn't notice. I've usually felt a lot more orgasmic - and my partners have felt it - with absolutely no internal thumping at all. I worried about this for a while, then decided the thumps are probably happening but I'm too preoccupied to notice 
I come from penetration, too. It's untrue that there aren't any nerves in there. Take a look at an UP TO DATE diagram of a clitoris - the thing is huge!
To be a bit more experimental, I think you need a playful attitude and circumstances in which you can 'lose' yourself a bit - so, no fears of interruption, not too much light if you're self-conscious, being warm enough and comfy enough. I'm sure this isn't good advice, but alcohol can help.
I've got a lively imagination and use it freely during sex. But, for me, it's just about trying on different emotional states, not escaping from reality: I can't stand sexy role-play! Different positions, speeds, textures and so on can be very pleasurable. The main thing is to stay comfortable.
Those looking for ideas could do worse than read teenage women's magazines. We all have to get tips from somewhere!