It depends what you and your mates like. My wife and I spent a week in Chester recently and that's not far. The River Dee is beautiful for walks and rowing and there are lots of tours such as the Roman tour of the city, the Saxon tour etc.
If that's not your thing, then we went to the Inland Waterways Museum at Ellesmere Port. It's the largest inland watercraft museum in the world apparently. There are lots of preserved narrowboats, barges, cruisers etc and they run trips too. It's also a museum of canal life with workshops, working steam engines and other things. There is also the Blue Water Aquarium at Ellesmere Port.
Failing that, north Wales and Anglesey maybe. Llanberis is quite impressive with a slate museum, Electric Mountain and the Snowdon Railway. Anglesey has Beaumaris Castle and Puffin Island boat trips.
That's a few things we did there. Hope it helps but it does depend what sort of things you like.