Yes, you'd meet interesting people, and what kind somewhat depends on your cabin class - as you know, Cunard ships are open everywhere except the assigned restaurants/lounges for Princess/Queen's Grill pax). A cross-section of folks in the regular cabins; more of the pacesetters in the pricier ones. I daresay you'd find a fair share of singles/couples on any one cruise.

With a companion, I did the QM2 eastbound crossing in fall 2008. Just a regular balcony room assigned to the main restaurant, so we met the hoi polloi, mostly 30s and up, singles and couples. The nightly Friends of Dorothy cocktail hour is good for meeting others from all cabins; on that cruise, about 20-30 of us mingled nightly for cocktails, chatted about the day's activities & dinner plans & the next day's schedule. We happened to hit it off with a Canadian gay couple on board to celebrate an important B-day in style, and found ourselves spending significant time with them. Others we liked included a single, young lawyer on holiday before starting work in NYC, and a middle-aged author and his younger companion. The staff is definitely gay-friendly.

Routine at sea: With no ports of call on the QM2 crossing, the focus is on shipboard activities. Plenty to do, or none-at-all for a delightful rest. Evenings are usually dressy - 2 or 3 evenings are designated Black Tie. There are 2 dinner seatings for the main restaurant; the older crowd generally prefers the earlier seating (then a show, and off to bed), while the later seating is more convenient for leisurely cocktails, the late show, casino/nightclub until the wee hours.

I've cruised enough (happen to be Cunard Platinum) over the years by myself, and with a companion ...and it's all about expectations. Being realistic means rarely being disappointed.