The FBO I learned to fly at was a very active Piper dealer and always had older PA-28s of various types in rental while they were listed for sale. So I got to fly a lot of different PA-28s.
The PA-28-140 and 150 are two seat aircraft. Some just happen to have rear seats. Think if it like you would a child seat in the back of a C-150 or C-152, except ok for 2 kids - small ones.
The PA-28-160 B and C have 2200 pound gross weights and from the factory had around 1210 pound empty weights so 980 pounds useful load (at best - they all get fatter with age), but small back seats.
The PA-28-151 Warrior had a more efficient semi tapered wing and a longer cabin that made it an actual 4 seat aircraft. Gross weight was 2325 with empty weights around 1335 pounds for a useful load in the 990 pound range. With 294 pounds of fuel with full tanks, it had about 700 pound left for people. If I had four adults on board and no baggage, or three and a lot of baggage, I just filled it to the tabs (36 gallons IIRC) and kept another 100 pounds or so available for people and baggage. However, even with the same loads on board and similar useful loads, I always felt the Warrior flew better than a Cherokee 160 even with 10 less horsepower.
The PA-28-161 just added 10 more horsepower with the same weights and useful load, so it was a win-win, but not so much that I'd turn down a good 151 for a less good similarly priced 161. Both are super easy to fly and with a wing leveler long flights are very low workload.
The PA-28-180 B and C had a 2400 pound gross weight and an empty weight only about 20 pounds heavier than the 160, so around 1170 pounds useful load - but still the small back seats.
The PA-28-180 D E and F gained weight with empty weights around 1310 pounds so the useful loads went down to around 1090 pounds, and still the small back seat.
The PA-28-180 Challenger and Archer had 2450 pound gross weights and 1400 pound empty weights for a useful load around 1050 pounds.
The PA-28-181 Archer II had the semi- tapered wing and an gross weight increase to 2550 pounds and an empty weights around 1420, with a useful load of around 1130 pounds. That's four 200 pound adults, with only 10 pounds of baggage each, with full fuel, cruising at 125 kts. Or fill it to the tabs and everyone gets 35 pounds of baggage.
The PA-28-235 Charger (IIRC) had a shorter cabin and the hershey bar wing, the PA-28-235 Pathfinder had a longer cabin and a hershey bar wing and the PA-28-236 Dakota had the longer cabin and the semi-tapered wing. All three had a 3000 pound gross weight and useful loads in the 1400-1500 pound range.
If I were in the market for a do everything aircraft that was still reasonably cheap to maintain, I'd seriously consider a Dakota. It'll haul four 200 pound adults, each with 40 pounds of baggage and full fuel and do it with a cruise speed of around 140 kts.
If I wanted something a little less expensive to fly and maintain, but still needed to carry four adults on a regular basis, I'd get and Archer.
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You also asked about the 260 Comanche. I don't have much Comanche time, but they impressed me as very nice, efficient aircraft to fly.
A 180 Comanche will have a 2550 pound gross weight, about a 1000 pounds of useful load and cruise at about 140 kts.
The 250 Comanche has a 2800 pound gross weight and an 1100 pound useful load and cruises at about 157 kts.
The 260 Comanche has a 2900 pound gross weight. The 260B GW increases to 3100 and the C increases to 3200. Useful loads increase from around 1175 to 1375 to 1425 pounds.
The 180 Comanche will haul about 100 pounds less than an Archer, but haul it 25 kts faster, in exchange for the increased maintenance and insurance costs of the CS prop and retracts. It'll also fly as fast as the PA-28-235 variants, burning less fuel.
The 250 Comanche matches the Archer's useful load and is 30 kts faster, and it's a good 10-12 kts faster than a PA-28-235, but with less useful load.
The 260 B and 260C Comanche are probably the sweet spot with the C having PA-28-235 useful load and a 160 kt cruise speed. The B is a just a couple kts slower with 50 pounds less useful load.
Subjectively, IMHO, the Comanche flies a lot different than a PA-28. It feels like a much heavier aircraft on approach, despite similar gross weights and stall speeds to the PA-28-235. It might be an artifact of my limited time in the Comanche, but it struck me as being more demanding to fly and one where you needed to be on your game and fly it regularly to stay safe. Much like the Bonanza, and I think the insurance rates will probably reflect that. On the other hand it had great feel in the air - very Cadillac like.
