How far do you want to
- travel in miles or time?
- do you need there to be public transport (rail, train etc?)
It would really help to know.
Woodchester Mansion - trees, some water bodies, part build Mansion entry extra cost (not sure if you can photo in the building or not). I think the grounds are run by the NT and used to be free of charge.
Newark Park - NT, trees, buildings, flower borders, country walks, nice outdoor cafe
Bisley - above Stroud. Well dressing in May, amazing cottages, 2 nice looking pubs and a cafe in the post office run by nice folk.
Cirencester - Roman amphitheatre (free access all the time), wood near amphitheatre, large parish church, good park at back of church with water body, riverside walks, the local lord lets people walk through his estate which is huge - opens around 9.00am closes at 5pm (I presume its one of those inheritance tax dodges?). Various events at Cirencester round the year including polo, check internet for events.
Stroud (has train access) - Old areas, away from the High Street, Canal walk. Involves lots of hilly and quaint residential areas , Black books cafe is the right direction (nice owners, pleasant environment).
Stroud - Stratford Park - sports, trees, lake, fantastic walled garden stacked with flowering plants / free museum.
Buy your ice creams from either the indoor pool cafe or outdoor pool reception, its a pound dearer for the same product if you buy from the museum. If you use the indoor pool cafe (which also seats outside!) you need to ask or search for the hot food menu, they only seem to have one copy which seems to end up in random places. The food there is nicely made basic stuff. Lady in charge is really helpful and nice. Hot food finishes at 6.00pm I think, snacks at 7.00.
Stroud/Nailsworth traffic free bike and people path - for nature stuff, can make it a circuit by retuning along lanes above it full of cottages. Fairly flat so may suit people who cant do hills.
Nailsworth - small town with lots of facilities, good centre for walks around lanes or bridleways
Tetbury - lots of nice buildings, walk down by 'The goods shed' new arts centre, free parking there, 5 min walk from town.
Minchinhampton village & common - old buildings, cows/horses on common (not winter), orchids and wild flowers (spring), kite flying festivals, long views, cafes, ice cream sold from the factory and nice pubs. Village shop etc for refreshments too.
Lots of other small villages, linear lane developments around Minchinhampton / Rodburgh and Selsey Commons
If you want to do nature, Woodland Trust have a search engine for public access land (not just their own land).
Forest of Dean - loads of locations for nature, preserved railway, water bodies, towns etc
Various villages on the North and South banks of the Severn.
Wotton-under-Edge - small town, can go up various hills and walk through to Nibley Monument and village. Town does fantastic charity tea and cake in town hall every Sunday in the Summer run by some really nice folks.
If you want flat places
Slimbridge Wildfowl Trust for ducks etc
Frampton on Severn - has a local show late summer and is the longest village green in England. Old houses, canal walk at the back.