Would it be cheaper to forgo the rail pass for this itinerary?

You can click on the "Railpasses" tab above to get information on the cost of point to point tickets.

A better source might be: http://www.railsaver.com/main.asp

Amsterdam - Gent, 39 Euro (Belgian Railways). Gent - Bruges, 5.90 euro (same source.) Bruges - Brussels, 12.90 euro (same source.) Brussels - Koln, 36.50 euro (German Railways), Koln - Amsterdam, 56 euro (same source.) These are for second-class walk-up ticket purchases, for a total of 150 euro, or about $200. Better prices can be had at the German railway website (Deutsche Bahn) for Brussels-Koln and Koln-Amsterdam, if you plan ahead....as low as 19 Euro. That would bring your total down to 96 Euro, or about $130. The rail pass tab and railsavers don't give the accurate point to point prices that you can find on the national rail websites, and they definitely do not show any sale fares. They exist to sell rail passes.

Thanks Norm, that is very helpful. Would it be best to purchase specific times on those sites now before our trip or just walk up and buy them? I'm assuming there are plenty of trains between those cities as they are popular routes

To get the cheapest fares on the German rail website the tickets will be non-refundable and non-changeable, so if you are locked into your travel dates and times, then you can do that. If you aren't locked in, probably best to just buy them a day or two in advance, or when you know for sure. With the cheaper rates, comes the extra conditions, so it's a give and take that way.

Have a good trip!

Jed's correct....the 19 Euro specials do have conditions; a 15 Euro exchange/refund fee up to the day of travel. But, since you'll be in Belgium, there'll be nowhere to get a refund or change if you change your minds at the last minute. Buying the other tickets ahead depends on 2 things....your comfort zone, and when you're planning to travel. Fridays and Sundays can be busy, as can holidays (of which there are a plethora in Europe in the spring and summer such as May Day). The German rail system is the best resource for checking schedules all across Europe (altho you can't buy all your tickets there.) Run thru your itinerary and see how many trains/day cover your journeys. If you don't mind missing one train and waiting for the next, then wait until you get to Amsterdam (for Gent), and Gent (for Bruges and Brussels). Depending on how important it is for you to catch a Brussels-Koln train, see if you want to book ahead of time. Koln-Amsterdam, if there are enough trains/day on the day you plan to travel, can probably be purchased on your arrival in Koln.

Expanding on what Norm said, I would not put to much stock in the recommendation from Railsaver. I have tried their analyses a few time, "just for fun", on trips I have already made and know what I spent, and I have never found them to be accurate.

First, they only seem to know connections to major, well known towns. If you put in a lesser known town, it won't know what you mean.

Second, as Norm points out, there are a lot of discount fares and day passes available, particularly in Germany, and Railsaver doesn't account for these. They are only comparing a railpass (which they want to sell) to full fare tickets.

Lastly, if you try them, make sure you check "Only if railpasses save me money.". The default is "If railpasses provide the best combination of convenience and price", and I have never seen railsaver say a pass was not the best combination, even when it was far more expensive.