We are so undecided about what to do in Glasgow and Belfast. Wether we should get a private tout or take the hop on hop ff. maybe there isn't even much of a difference in price since we are a party of 6.
There's a lot to see in Glasgow on foot or on the hop on hop off bus. You can do this by yourselves. Get a copy of the Rough Guide Scotland. Its chapter on Glasgow will be a big, big help.
What do you want to see in Glasgow. As Monte points out there are lots of sites. There's the Cathedral, there's the Riverside Museum that includes the transportation museum with its newly designed building by Hadid, there's the Tenement House Museum near the art school; there the magnificent Burrell Collection at Pollock County Park; there's Kelvingrove. If you look at the Hop on Hop off Bus map you can see that a lot of the stops are the hotels and you can see the city has generally three areas: The West End (Kelvingrove, Botanic Gardens, Hunterian), the city centre which is big spread out, (West to east, Tenement Museum, art school, Willow Tea Rooms, George Square, Modern Art Museum, Cathedral and a little dip south to the People's Museum and Merchant Square.) The third area is the riverside, including the transport museum and the science museum. And this does not include the Burrell Collection which is out of town a bit. If I had only one day in Glasgow, I would not try to see it all. Rather, I'd pick a couple of these areas to explore. It looks like you can do the whole circuit in a little under two hours without getting off, so you can see it all in the AM and then choose a couple of places for more in depth exploration. Just remember your geography. : )