Don't inflate a raft for fun - the inflation process involves a lot of cooling of the gas coming out of the bottle and this makes the rubber brittle, which is not a good thing in the long run. When the overhaul company (e.g. SEMS) tests a raft they inflate it using normal air, not by emptying the gas bottle into it.
Regards getting into a raft... there is a big spectrum of people out there, so please don't generalise.
To be perfectly honest many people are so unfit (or simply inflexible, through age etc) they can only just get into an aeroplane. I fly a TB20 and very much enjoy flying with some definitely senior citizens, yet some of them can only just get in or out of it, and a TB20 is no challenge at all for somebody able to lift one foot about 2ft above the other one.
Looking at today's ageing GA scene (at 50 I am one of the youngest) it's obvious that many pilots would not get out of their plane in a hurry, and getting into a raft is much less likely. I have no illusions about the survival chances of some of my passengers - if they ditch, they will most likely go down with the plane.
I reckon that if you picked an adult off the street at random, they would find it at least slightly difficult to get into a GA piston plane - well maybe except a C182. Into a raft? Not much of a chance. So many people these days are so overweight they can barely walk up steps.
But this does not in any way negate the value of a raft, for those who are reasonably fit and flexible. There is indeed a knack to getting into one - if you start off in the water; you have to "roll in" more or less with the whole body in one go and not try to climb in in the obvious way (upper body first) because it will just tip over backwards, onto you. Anybody who messes about on the water (dinghies, windsurfing, etc) especially in any reasonable sea state will know what I mean.
Ideally one would try to get it inflated close to the aircraft so one can step into it, but this assumes you can all make a rapid exit. Out of a PA28 (or any other single door plane) carrying 3-4 people, forget this option.
The sea state is a valid flight planning option too. Would you fly over sea when it's blowing F10? Ditching in that would be exciting enough, never mind getting out.
The great thing about a raft is that it can just sit on the back seat, ready for use. The U.S. Survival Products ones weigh under 10kg which in terms of W&B is probably about equal to the size of the lie in your female passenger's declared weight
Drysuits will absolutely not be worn by 99% of people especially "normal" passengers, so their benefit is theoretical.