The open house does not include a SIM ride. If they like you, you will be asked to finish an interview and SIM in SLC. For that, we use the ATC810. It's a real gem and the only reason that it will not be in DEN or any open house is that it would probably fall apart if moved from it's current location.
I'm not sure of the exact name, but believe it's American Aviation located on the GA side of the SLC airport. They do interview preps in the ATC810 the day prior to the interview. Honestly, I think that if you bought a couple of hours in any ATC810 and did several holds, and approaches you'd be fine. Make sure that you can do non-precision approaches and PLEASE enter the hold correctly.