as far as I know, most smaller airfields, like Texel, Teuge en Seppe are usually very friendly for spotters/photographers. If you contact them in advance, I'm quite sure they can help you out with somethinghttp://www.scramble.nl/airports/index.html
you should check this site. It's really good for logs and expectations of all Dutch airfields and has a lot of detailed descriptions of all viewing areas.
Amsterdam tends to get a big pain in the backside lately, with the best spots closing and all sorts of traffic regulations. By bike or public transport, it probably your best bet to get to the runways (that's what I do as well)
For military airfields, all of them have good photospots. Leeuwarden and Volkel even have official viewing areas. Mil traffic is very slow on regular days, with maybe 2 waves of 4-5 F-16's and a few helo's at Gilze-Rijen. Your best bet is to come over for regular exercises like FWIT or Frisian Flag (or a one-off like the NTM at Volkel)
hope this helps you a little,