If your frame can fit them, 32-35 mm tire width hits the sweet spot, IMO between comfort and efficiency. Folding bead definitely helps with rotational weight (lower inertia).
A larger tire casing will provide better comfort and more secure handling than a skinny tire, without sacrificing much in the way of rolling resistance.

The rest of the formula is your own fitness. As your fitness level improves, you'll find that the hills aren't so bad, after all.