I'd never heard of Seis, but worked out you mean Siusi (all places in that area have three names; Italian, German and Ladin versions). That's a great place for a base, loads of good routes available from there, including the classic Dolomite passes. The massif above Siusi is stunning, the first time I rode in that area I rode up to Siusi from Bolzano and as you started climbing out of the valley floor, the scenery just got more and more amazing.
For a second base, I'd possibly look a bit further east, around the Pieve valley, but its so long since I was last there, that I don't know what any of the villages/towns are like nowadays.
I'd never heard of Seis, but worked out you mean Siusi (all places in that area have three names; Italian, German and Ladin versions). That's a great place for a base, loads of good routes available from there, including the classic Dolomite passes. The massif above Siusi is stunning, the first time I rode in that area I rode up to Siusi from Bolzano and as you started climbing out of the valley floor, the scenery just got more and more amazing.
For a second base, I'd possibly look a bit further east, around the Pieve valley, but its so long since I was last there, that I don't know what any of the villages/towns are like nowadays.