Can anyone recommed a good hotel in Prague? I am planning a trip in April.

what's your budget?

Mid-range. Less than the Four Seasons.

Are you willing to use a discounter and possibly get a "standard" room?

I did quite a bit of research and decided on the Prague Renaissance (run by Marriott) since it seemed like the best value for the money and location. I would have preferred the Marriott itself but it was a bit more than I wanted to pay. A friend of mine who has been there a few times recommended the Holiday Inn Crown Plaza. at Koulava 15.
Tele (+420) (0) 2 24393111 Fax (+420) (0) 2 24310616

I usually pick business hotels because I have found the charming hotels in Europe usually have charm but poor amenities or customer service training.

Hi
I don't know if these fit your idea of mid-range, but I've been researching a number of hotels here and at tripadvisor.com
I stayed at the Four Seasons last time but want something less expensive this time

those that seem to get univerally good comments include
the Josef, the Maximillian, and the Certovka. One notch down from those is the Cloister Inn.
All have cenral locations.

I think the Renaissance that Roman mentions is a good choice, if that's your idea of mid-range. It does have a very good location and is fairly newly renovated, so things are up-to-date and should be working. I do like the Maximilian but that might not be your idea of midrange (prob Renaissance is higher, also).

There's a decent Best Western right around there, also in a good location (Meteor Plaza). There have been a lot of good hotels opened in Prague in the last 5 years or so, a lot better than before. A lot of the older hotels, even if 3-4* or not that cheap, did used to have questionable charm.

I just got back from a stay at the Maximilian and liked it a lot. The location is ideal, just a short block or two from the Old Town clock, but on a quiet street across from a lovely church.

I thought it was a very good value at 149 euros per night for a twin room (through expedia - we couldn't get that rate through the hotel itself), and that included a very good hot buffet breakfast - much better than the standard hotel breakfast we had at all the other hotels where we stayed.