Bring money if you hike up and want to ride down!
The hike up Sulphur Mountain was just right for my family (including a six year old). It can be done in about 2 hours if you're all in decent shape, but parts are quite steep and the trail is narrow at points. (I'm afraid of heights but somehow managed to do this hike. It was a bit dicey for me at times.) We went in May 2006, before the supposed "busy" season, and I can confirm that they do charge for the gondola ride down (something like $12 for adults - kids 5 and under free). It snowed and hailed when we were at the top, and that was pretty kool. Bring an extra jacket.