I have not been yet, but have read A LOT of trip reports, etc.. It seems that quite a few travel by themselves to Peru. I have traveled to both Argentina and Brazil by myself without any problems.

I think 6 full days (i.e. not including your travel days) is enough time to see MP and a little of the SV and Cusco.

ps check out tripadvisor-- there are many more posts and people to provide you with advice than on this forum.

thanks! good to know its ok to go by yourself! Was wondering! I was thinking of doing an argentina/brazil tour but its quite expensive. Thinking maybe go by myself and have more money and choice but unsure if ill be bored! Any recommendations?

Well, as for boredom, that really depends on your personality and how you like to travel. I like travelling alone. You meet people, can go on your own schedule, etc. But, if you don't like to talk to strangers, or get bored sitting in a cafe by yourself with a journal or a newspaper, or hate seeing sites if you don't have someone to share them with, traveling alone may not be for you. My boyfriend and I both like to travel solo, as well as together, so we go some places together, and some places on our own. But we have friends who wouldn't think of going on vacation by themselves.