Travelling around Europe or USA?

I am a complete newcomer to travelling, but as it's my dream, I want to save up and go summer '09 for a month. A couple of friends may be interested on coming along but I can't bank on it.. so I was possibly thinking of buying an 'outright tour' and thus, seeing many countries. Contiki.com do some great ones. Is this more cost effective, or is it better doing the inter-rail, hostel malarchy??? Please help!

I'm interested in Western Europe and Southern America- LA to NY

Ps. I'm British.

i went around europe last summer on the interail for 5 weeks it was great - i went to copenhagen hamburg wacken festival berlin warsaw krakow oswiem budapest vienna venice rome cinque terre genoa pisa monaco geneva interlakken paris amsterdam.
ive also been a few more places so if you want any more info just add it.
europe is great and its much more compact then america.

i seriously recomend interail it gives you more freedom

Either can be good... I mostly stay in youth hostels and I did the classic travel around Europe via interrail in March. It was fun... the one drawback though is that you do have to cover a lot of ground to make an interrail pass cost effective and I got a bit sick of trains by the end. You have more freedom with passes but you have less stuff to worry about with a tour. Also with tours you stay with a set group of people for a longer period of time (in my personal experience the interesting folks I meet in youth hostels tend to be heading in the opposite direction that I'm going...)

As far as Europe vs US... Both can be fascinating. When you say LA to NY do you mean Los Angeles or Louisiana? The one drawback to doing the US in one vacation is that a lot of the middle of the country is not that interesting... You have to go and do things like California and the Grand Canyon before you die, but Nebraska and Missouri and the Texas panhandle you can pretty well skip. I'd recommend doing one coast or the other, or flying from one to the other instead of driving...

As far as costs are concerned you at least don't need expensive plane tickets to get to Europe.