The Southwest coast path starts on the South side of Poole harbour entrance and goes all the way round the coast to Clevedon on the Bristol Channel.
I'm not suggesting you do the lot in a couple of days, but there are some very good sections on the first part from Studland down to Lulworth Cove and beyond. Main problem is picking you start and finish points for the day or part of day you want to walk.
Ideally you need to start say at some location served by a car park and/or a bus service. The idea being to park, then walk x miles to a place you can catch a bus back to the car park, the alternative being to walk so far then turn round and retrace your steps to the car park.
Once you get past Swanage there are few if any bus routes that run every day.
Studland along the north side of Ballard Down out to Old Harry rocks and then continuing along the south side of Ballard Down to Swanage, this is mainly cliff top walking;
From Studland to Old Harry you will mainly have views northward across Poole bay with Bournemouth in the distance, or if a clear day then the Isle of Wight may be visible. Old Harry rocks themselves are worth a few shots. Along the south side of Ballard down views to the South and West across Swanage bay, Swanage itself has quite a few photo opportunities and some excellent chippies.
Continuing south from Swanage back up onto the cliffs, there is a wild life centre (Dolphin watch) at Durlston head. Also some caves, but I'm not sure if they are still accessible.
Turning west you pass Dancing ledges, rock ledges that extend a bit out to sea, then comes Seacombe, the Winspit St Albans head and Chapman's pool. Just inland from these is Worth Matravers, don't miss the Square and Compass, some years it gets voted into best pub in the region and once made national winner. Views on this section will be mainly along the coast, nothing to see southwards apart from the occasional boats.
Buses occasionally from Worth Matravers to Poole or Swanage IIRC.
Inland a bit you have Corfe Castle ruins, the Swanage preserved steam railway, Wareham and quite a lot of villages. All building in the area must be done with the local Purbeck stone which makes for some very nice cottages and houses.