trying to get the feel of old times in the netherlands outside of amsterdam

Your 4,5 days is not much, and I'd say you've got those days already pretty much filled.
Haarlem is a 15-minute train ride away. It's - after Leiden, of course - one of my favourite cities in this part of the country. You should avoid Marken and Volendam at all costs. Monnickendam is a nice, small town on the former Zuiderzee. A 20-minute bus ride from the bus station at the back side of the Centraal Station (http://9292.nl/en# for schedule). Hoorn, another harbour city, has more grandeur. The half-hourly intercity from Centraal Station takes some 30 minutes.
And if everything else fails, there is always Leiden...

Another vote for Leiden - one of our favorite day trip destinations as well. Go to the Pilgrim museum there - fascinating place.
You might consider exploring the surrounding countryside in true Dutch fashion via bicycle. The Waterland area just across the river (behind the train station) is beautiful - flat Poulder country all the way up to Marken, which we also enjoyed as a lunch stop and turnaround point - really a fun outing on a pretty day.
Bikes can be rented next to the train station and then taken across on the free pedestrian/bike ferry, thus avoiding having to negotiate any streets in the city.

Three different canal tours? If they're all in Amsterdam, I'm not sure what would be different among them.

I also highly recommend Leiden. My other strong recommendation is for Utrecht, with its unusual bi-level canals and several good museums. There's the Rail Museum, the museum of music boxes and fairground organs (a docent demonstrates all the music-making contraptions - great fun), and the Centraal Museum, with everything from ancient ships to modern art.

Since nobody actually abused Delft for being too touristy, I'll mention Alkmaar, which is not "more" touristy. I guess Utrecht is not historic enough, but it has nice museums. I'm fond of Amersfoort, but the medieval section is heavily "redeveloped". A bit farther, Deventer has a magnificent old-town square, with a nice local museum. But it's a bit far. And just five blocks from the old square is a one-block "red light" zone.

Deventer's square is perhaps the most "authentic" of those listed so far, but I don't know that it's worth the travel time. I'd go to Leiden, because you can't see it all in a full day-out. BTW, you didn't mention "art history", so I assume that's not important.

It would make sense to combine Delft and Kinderdijk, if possible. Delft's square is bigger than Deventer's, but Delft's more polished up.

Both Leiden and Haarlem have their attractions. Haarlem is maybe the »nicest« of the two cities. Beautifully situated on the Spaarne river it has a beautiful market square and the superb Frans Hals museum. The strong point of Leiden are the canals. The Rapenburg has the grandest houses of the city, and the Oude Vest is the most impressive one.

To the hijacker: I don't know how to combine the public transit, but if I wanted to go to Keukenhof, I would probably want to see the nearby Aalsmeer Flower Auction in the early morning. There's a satisfactory cafeteria at the warehouse for indoor lunch before going on the afternoon at Keukenhof. Some visitors find Keukenhof less crowded in the morning.