The Route - still not quite certain

So I have 3 months - assuming I leave at the end of May - possibly earlier - I'm going to stick around for a while to earn enough money for my ticket and the actual trip - besides, I can't go anywhere until I know for sure that I've been accepted in a grad school. So I've given myself an approximate time for 3 months - which is probably too short to see the whole country, so I'm thinking of doing the whole northeast belt - from Kashmir to Assam and the north eastern states. I still haven't even started researching the sights. I should pick up a lonely planet - does anyone know which one is better rough guide or lonely planet ? My parents have always used lonely planet - and it's very effective. But reading reviews on Amazon, it seems as though the Rough Guide is better. Hmm...decisions decisions...