Upper reaches of the Hamble (launch at Swanwick and let the tide take you up), nice pub up the top at Curbridge. Beaulieu River; they'll charge you a fortune to launch at Buckler's Hard but you can get right up to Beaulieu with the tide. Studland Bay (though I think the NT have banned motor driven - including outboard - craft from the beaches). Maybe Christchurch Harbour, though the tidal window is somewhat brief, I think. Bosham Harbour always looks nice but - again - very tidal.