biz_fish
Look at it another way - if you train on the PA28 you won't have to convert to another plane to take more people with you.
The 'lightweight' PA28 easily copes with 3 people and those with the higher all up weight (of which BAFC) have 2 can take 4 without too much problem.
Of course then there is the Dakota which gives you a real 4 seater capability plus luggage, hours worth of fuel and a genuine 135 kts cruise - and they have one of those too!
After a few hundred hours in Cessnas and now flying PA28s occasionally (I have a homebuild to fly for fun!) I do feel the Pipers are a more substantial, 'grown up' aeroplane. Sit in a C152 with an instructor and then try the Warrior and feel the extra width for starters!
PM me for some other thoughts if you like.