I have several different size saws at my disposal but the best I think for general camping is around 18" but I have been known to bring along a 26"bar and chain as well as a 20" for for general stuff on a bigish saw so if there are big logs over the road it's a 5 min job to bolt on the big bar and away we go.
Make sure you get a complete sharpening/cleaning kit, round file to suit which chain your using, flat file to cut back rakers, raker guage and an angle guide as well as the proper sparkplug/bar clamp/bar adjuster tool a small paint brush.
Always use good quality 2 stroke and chain and bar oil, not just sump oil or engine oil as the sump oil can bugger the bar oil pump as normal engine oil doesnt provide the same lubrication as 2 stroke oil so it can damage your engine as well as the detergents tend to turn into little carbon balls that get caught in your plug gap and can be a general PITA.
Personally I prefer to buy quality chainsaws/equipment as mine tends to get a thrashing but that looks good enough for what your wanting.
Go and do a chainsaw course, it is worth the money as you cant buy a new arm or leg and your family cant go and get a new you if you get it wrong.

