I typically won't share a room, but I'll be flexible depending upon the situation.
I was with my previous company for about 8 years, and it required
extensive travel...however, I was usually by myself (engineering field work) for whatever project I was on. I think I shared a room 3 times in that whole period -- once was when I was being trained and was visiting some jobsites in the first month of employment with a sr. engineer. He was handling all the arrangements, and it was an overnight trip. When it came time find a hotel, he booked us a double/double in something like a Days Inn -- not fleabag roach motel, but COME
ON. My (silent) reaction was, "WTH kind of company have I signed up with?"
Turns out it wasn't a company requirement or even SOP; he was just trying to keep costs down for that particular trip. I actually did the same thing some years later when training new engineers or techs...except I'd book a two-bedroom suite. Room-sharing was typically a function of project budgets; that company had a lot of small (<$25K) projects where lodging was budgeted around $100/night, and usually only required 5 or 6 nights total over the length of the project. I typically had total control over project costs, so I could stay wherever I wanted...but if I blew the budget it was my rear end in a sling.
The only other time I shared a hotel room was on a project in Miami; it was a month-long project that required two engineers for the duration. The project manager went down with us to kick off the project, and rather than just stay in hotel rooms, we looked for something that would be more suitable for a long-term. We ended up getting a 3-bedroom 2-bath suite at a brand new development in South Beach - WITHIN the project budget (it was off-season).
Didn't mind sharing that one.
In fact, at the time, I was four months out of school and sleeping on the couch of a 2-bedroom apt with 2 good friends of mine until one of the guys got married that summer and moved out. The original project plan had been to rotate engineers in and out every 2 weeks so no one had to spend more that 14 days away from home; however, after about 4 days I called the manager up and said, "I think it would be better for continuity if you just kept me on this project for it's duration. It's no problem. REALLY."
I was the envy of all my recent-graduate friends.