Hi Gerry & Joy
I suppose it depends what you want from Amsterdam.
A few days in such a central location will be very convenient for seeing some major sights (including the red light district - which I'd recommend visiting to make your own minds up on the conundrum). It will also expose you to some of the more 'in your face' elements of Amsterdam, and can leave an impression of a bustling city of great life, but sleazy/grimy with it. For a first trip it makes sense to stay there, as staying centrally really gets you thinking about what the city represents.
For us we've happily gravitated outwards, generally staying out beyond the Museum Quarter, in more leafy suburbs that offer a lot more peace and quiet. It's a tram journey into the city, but when we've needed to go into the city, we go with a firm plan in mind. Plenty of great places to eat in the suburbs, and PC Hoofstraat has very civilised shopping. Other places I'll always shop on are the 9 streets, and Kaaskamer on Runstraat is one of my favourite cheese shops in the world. I'm a big fan of the Ethiopian restaurants, the one we liked most was on a road off Overtoom. However the range of overseas cuisine is exceptional.
Vondelpark is another good place to relax, as although it is vibrant and popular, there is loads of space and the greenery is much appreciated in a built-up city.
How many days? It's a big city and it would be difficult to run out of things to do. If focusing on the centre, then I'd suggest at least 3 days, but up to a week could easily be spent centrally plus just a few trips to the suburbs e.g. Museum Quarter, Albert Cuypstraat market, etc. More than 7 days and I think I'd find the centre too busy/noisy/imposing. Day trips out can help break it up, and the train system is excellent.
Regards
Ian