Rich

Yes can see some, yes. If they're doing anything sensitive they drop off the radar, but there are usually a few to be seen. 

Worth also watching the firefighters; water bombers and spotting aircraft. 

It's not usually possible to see the fast jets doing operational stuff or operational traiing, at least for me.  But if you want to watch fast-jet training, try west Texas (T-38s) and Snowdownia (Hawks, mostly from Valley).  Sometimes you can see the electronic targets over the North Sea, but not often the aircraft flying interceptions.

Sometimes you get exotic stuff too.  Hurricane hunters (mostly P-3s) over the Caribbean).  NATO AWACS and reconnaissance aircraft over Bulgaria.  Spitfires, Mustangs, SAAB Tunnan.  The Canadian Lancaster when it came to the UK via Iceland.