Add Prague to a trip to Belgium and Netherlands?

I wouldn't do it, unless you can fly into or out of Prague in the beginning or at the end of your trip (no separate flights back and forth between Prague and Amsterdam or Brussels - and maybe not even then.

Ten days means nine nights in Europe? That is not much time to try to see parts of Belgium and the Netherlands, without seeing just the highlights of the biggest cities.

And as much as I love Prague, I would hate to see it so overrun with tourist mobs in the summer - it was bad enough in September, where it was hard to walk across the Charles Bridge without bumping into people!

Thanks Andrew.
I appreciate the thoughts. As much as I would love to go for longer, just can't, and I want to make the most of the time. I really want to see Prague, but trying to squeeze in may just be too much for this trip.

I guess if I were seriously considering this, I'd put together both itineraries: Belgium and the Netherlands or both those plus Prague. What would it look like? Good flight connections? How much time do I lose? What am I giving up by adding Prague?

First of all, what are your interests? What type of things and which cities do you want to see in Belgium and the Netherlands? My guess is that you will find more than enough in those two places to fill your days. You also need to consider your travel time between the various places in those countries alone. Prague is my favorite large city in Europe. We spent five nights there, and I wish we would have had a bit longer. With the limited time that you have, a visit there will not even begin to scratch the surface. I would encourage you to experience Belgium and the Netherlands on this trip. Save Prague for another time in order to give it the time that it deserves.