One good walk you can take is to keep walking uphill from Vashisht to Bahang (past the lovely waterfall and weird meditation tarp camps), then cross the river to Goshal, turn right to Shanag, Burwa, and then to the Solang valley.
In the Solang valley you can do some adventure sports, including paragliding (which I think is somewhere between hang gliding and parasailing?). There is also a bus back to Manali, although a kind paragliding pilot offered me a ride back on his motorcycle instead. So if you want to do some paragliding, Ram (9816170161 or email ram_skyrider at yahoo) is at least a nice fellow.
Manali seemed like a holiday spot popular with Indians. I'm told it's also a popular honeymoon destination. (Leh, on the other hand, is about half white people. These are both fine.)
In looking for services (hotels, trekking guides, travel agents, internet, things to buy) it seems like the thing to do is just avoid getting bamboozled, as most folks are pretty straightforward, and most services are comparable. Avoiding getting bamboozled is mostly easy to do. (it has been easier in Manali and Leh than in Delhi.) Nevertheless, some recommendations: Valley of Gods were helpful with travel planning, and Hotel Bhrigu was good.