The best way to visit Holland is by bicycle. You can rent them about everywhere (also at train stations) and there are beautiful cycle paths. At the tourist information you can buy special cycle maps.
For instance: from Amsterdam, cycle along the river Vecht all the way to Utrecht.
Another great one is the Blossom Route, do it in april/may and watch the blossoms along the river Linge, around Culemborg.
If you have one extra day to spend, take a trip to Utrect. It is about 40 minutes by train. This little university town has most of the offereings of Amsterdam; the canals, cafe's, but the best thing is that Utrect is cleaner, more peaceful and more relaxed.
So if you have done Amsterdam, go to Utrect and take a break!