This is a pretty easy question. If you are flying to a station, then you need to carry stuff. So the rear door of the Cherokee six / Lance / Saratoga / Seneca II is invaluable. I've carried everything from car parts to coffee tables in ours. Can't do that in a 310 or Twin Comanche or Aerostar. The Seneca II has better loading flexibility than a Baron (only other twin with a rear door) and is cheaper in every regard. If you want to get above the bumps on a hot day, the Seneca will do that easily (unlike a loaded six). The SIDS programme makes any twin Cessna other than the T303 problematical in terms of both maintenance & resale. The Seneca II has good shortfield performance if you need it and (unlike the Comanche) parts are easy and relatively cheap. There is less labour in the 100 hourly's too. If you cruise it a Lance / Saratoga speeds (ie 45% / 55% power) the fuel burn increase is not much. At 8 - 10,000 ft I pretty much get 175 kts & 86 - 88 litres / hour. I moved to the twin after I did one too many outback flights at dusk. Once you've moved to a twin, there's no going back to a single.