What I do with my Slate plus when connect it to a hotel-WLAN: I connect the hotel-WLAN on 2.4GHz and fix the Slate to 2.4GHz.
For my internal WLAN I use channel 161 (SRD) with 80MHz bandwidth.
Until now this configuration worked in all hotels, whether they have password or captive portals.
Edit: I switch the Slate to “router”-mode when I use it in a hotel.