Check one of the route-planers, for instance http://www.viamichelin.com for possible itineraries, travel distance and time estimates.
One of the quite scenic itineraries is via Interlaken, Lake Brienz north shore for Susten pass to Wassen, then St.Gotthard (tunnel or pass). From Gruyères to Interlaken either via Charmey for Jaun pass or via Grandvillard, Montbovon, Saanen (possible short detour to Gstaad).
Other scenic, challenging option from Interlaken is Grimsel pass instead of Susten, then to Ulrichen for Nufenen pass road - both great views, but lots of curves. Possible shortcut, is Furka pass road to Andermatt and then St.Gotthard. Furka mountain pass road can be scary for some drivers and passengers on the Uri side (from the pass to Realp)
If you prefer easy roads: from Interlaken via Brünig mountain pass road to Lucerne, from there to Andermatt for St.Gotthard. Easy option, imho nicer than St.Gotthard is Andermatt via Oberalp pass to Disentis, then Lukmanier easy pass road to Biasca.
Places to see (and stay) ? Plenty! Best if somehow interested in rural architecture and activities would be Ballenberg open air museum (near Brienz) - takes at leas a half day.
Edited: 7 years ago