You have four main options:
1. Platform pedals (traditional style). These work fine, but you can slip off in wet weather. I don't particularly love them, but they have worked fine for as long as bikes have existed. There is quite a wide variety of materials to choose from
2. Platform pedals with toe clips. Till the late 70's or early 80's this is how racers got around as well. I like using them i the winter on my bike. I ride in the Buffalo NY area. The winter is harsh on bike parts, I don't care to treat my SPD pedals to a regular diet of salt+sloppy snow+road grit. I'd be buying new pedals once a year. My toe clips are some sort of nylon plastic. I also have covers on them that realy help keep my toes a lot warmer. I ride in athletic shoes all winter long and rarely need full winter boots. I CAN ride in winter books, but the athletic shoes are much more comfortable
3. Full clipless pedal system. SPD clipless is nice because you can WALK on the shoes once you are off the bike. As you mentioned though this may not be a good option for you
4. Clipless with platform on one side. This may be an excellent solution for you. I have a set of Shimano pedals like this. I ride with my SPD shoes 99% of the time in the summer, but every so often I just need to climb on quickly and don't feel like swapping shoes. I can then use the opposite side of the pedal as it is a normal metal platform pedal. I got mine last year on sale at Performance Bike for $54.
As far as being more efficient on clipless shoes, I definitely can tell that I can both push and pull better with the Clipless setup, but toe clips not that bad. The biggest difference is that the clipless shoes are firmer and therefore you don't "feel" the pedal as much. My SPD shoes are on the more flexible side as I wanted shoes that I could walk in very comfortably. None the less, the SPD shoes do a much better job of supporting my feet when riding.
Happy riding,
André