Thresh Fest Anyone ??

Then go for Amsterdam, equally easy to reach. And isn't prog rare all over the country?

Amsterdam is not a likely place either due to lack of intrest from public, so the bookers won't book prog. Even metal is a rarity in Amsterdam.
last year i visited over 30 shows in Zoetermeer and only 10 or so in the greater Amsterdam area...

The only venues in the Netherlands with a good strong proggrowd are probably the Boerderij and de Pul, of which the Boerderijis the best accesible with public transport. P60 also had a good growd, but has lost it in the past few years.