osaka to tokyo - help with the in between

Hi
First trip to Japan at the end of April for 11 nights, flying into Osaka and out of Tokyo. We want to spend at least 4 - 5 days in Tokyo to see friends.... just need to get some help with the start how many days and where making our way to Tokyo.. e.g. are we best to base in Osaka and do day trips to Kobe, Kyoto, Nara etc or stay a few nights in Osaka and few in Kyoto? We are really easy going travellers and are not trying to do everything in a short period of time - what we see we see and if we miss we be for next time... thanks in advance!

If you are easy going and not working to a "tick everything of a list" then I would recommend to stay in Osaka and do day trips to Kyoto and Nara, and maybe Mt Koya.
Osaka will be a little cheaper, has great fun night life and eating, and is easy from which to travel.
Mt Koya is possible in a day trip, and worth it. Overnight would be even better.
Enjoy!!