We are planning 3 days in Tokyo and for one day would like to go to Nikko or Kamakura. We are going to Kyoto after Tokyo.
Frommers suggests to choose Nikko if visiting Kyoto. Any suggestions are really apreciated.
Also, any suggestions how to plan 2-2.5 days in Tokyo? Any recommendations for half day sightseeing tours?

Kamarkura

i would agree with frommers on Nikko, but note we did NOT go to Kamakura. However, we chose Nikko because it sounded very different from the more subdued and subtle style of the temples typical in japan, especially in Kyoto and we liked seeing that contrast. Nikko is by far very ornate - very Chinese influenced style, but in a lovely wooded/park setting.

As to Tokyo, depending on when u r there, the highlight for us was visiting a Sumo stable in the morning to see a practice VERY up close (Eyewitness guided has some write up on how to do that when tournaments are not scheduled).

I enjoyed visiting both Nikko and Kamakura. Nikko's temples and shrines are much grander and more ornate than those of Kamakura, and are somewhat unusual for Japan; Kamakura's temples are older and more humble, and more typical of Japan. Kamakura is in a pretty setting by the bay; Nikko is near Lake Chuzenji and the impressive Kegon waterfall. Hope that helps!

Both Nikko and Kamakura have interesting sights. Kamakura is a closer to Tokyo and is easier to get to via the metro system. With just 3 days, this travel time might make a difference.

We just spent two nights in Kamakura and it was wonderful. We went to Nikko last time in Japan so we decided on Kamakura for this time. If I had to choose one, I'd go with Kamakura.

Many thanks to everybody for advices. Is it possible to visit Kamakura on our way from Hakone to Kyoto? We are planning to go to Hakone from Tokyo and overnight there.

Hakone-Kamakura-Kyoto would be backtracking, as Kamakura is closer to Tokyo. You can do the reverse, ie Tokyo-Kamakura-Hakone-Kyoto, though I doubt you would enough time to do this. Tokyo-Kamakura is about 1hr train ride, but Kamakura is not served by the bullet train.