Better to make day trips from Amsterdam or to stay locally?

You can stay very busy as a tourist out of ams. Think museums, canals, walk to see architecture etc.
The city is a blockbuster for tourists. Stayin a b&b for ultimate dutch ambiance.
Haarlem, Edam, Delft are all close by train. But for sure see all of ams first. If unstill have time do the other towns. A wk is not enuf to see hague and ultrecht also, imo.

I would consider staying for about half the time in a city other than Amsterdam, both because you get to know a place better and because just about anywhere will be considerably cheaper than Amsterdam. Trains are great for day trips and not just from Amsterdam. The Hague is interesting, has fine museums and a beach, a 20-minute tram ride to Delft, easy to visit other cities by train, and is almost as close to the airport as Amsterdam.

I think it depends on who you are as a tourist. If you want to visit the tourist attractions and want to be entertained, you should just stay in Amsterdam and proceed by taking part in a bike tour in the surrounding area. But if you are more into the general atmosphere and the Dutch lifestyle, it won't hurt to visit some other cities or regions, too. Just be aware that there will be less tourist attractions in the less touristy regions. You will have to plan a bit more in advance, eg. using http://www.holland.com/us/tourism.htm .

Amsterdam is probably the most expensive city to stay. If you want to visit other cities and regions as well, you could consider staying locally, but you could also consider staying in Amsterdam 4 days and staying the rest in a more central located city like Utrecht, which has a large train station. You can get pretty much everywhere in the Netherlands using mass transportation and trains/busses run frequently (eg. every 30 mins), just be carefull not to miss the last one of the day. Websites that will help you plan your visits are http://9292.nl/en/# for all modes of mass transit and http://www.ns.nl/en/travellers/home for trains in particular. Fares are also being displayed. Of course, Google Maps will help as well.

So: it depends. The most tourist attractions are in Amsterdam, but by planning in advance you can discover a lot off the beaten path. Consider mass transit convenience when planning where to stay. Good luck!

May i just add train fares are expensive imo. factor in that cost on raileurope.com to see what makes sense for your itin.

Disagree that it is expensive to take trains around in the Netherlands. As Stijn posted above, mass transit trains & buses will pretty much take you just about anywhere and they depart frequently throughout the day. I think there is plenty to keep you fully engaged in just Amsterdam for an entire week, but it's very easy and cost-effective to get to the Hague or Utrecht if you did want to stay somewhere else for a few nights. Just depends if you want to pack up and move from your Amsterdam lodging. Both The Hague and Utrecht are easy enough to do as day trips if you choose to just base your lodging in Amsterdam for the full week, but as pointed out, Amsterdam lodging can be a bit more expensive than other towns and cities in the Netherlands. It's up to you to determine how you want to spend your time and your money.