Oh, boy. This will be my second year growing, and I'm almost the opposite to you, as I've been seduced by the Chili bug, so this year is mostly about one half of my greenhouse being taken up with peppers... in pots, like you. The other side is beds and, like you, they are set for tomatoes and cucumbers (half to be gerkins).
Ches mentioned melons. Have you considered cucamelons? I tried them last year and, even though I generally started my interest in growing a few months too late, the cucamelons still managed to yield masses that I picked for lunch snacks every day for a good few months from only two plants in one bed, but you could use grow bags, maybe? I cleaned my beds out over the holidays, and their roots were very shallow. Like cucumbers, I assume.
This year I want to try growing black pepper in big pots with custom trelaces. From my research it might be two years before any yield, and I'll have to move them indoors during the winter, but it seemed like a fun challenge. Maybe do peppers, but in a whole new way? They yealds seem to be very good, once/if you get there.
Maybe get some long containers and double dip salad greens that don't easily bolt for early crops to snip and come again, and then re-use the space later for late summer/early autumn fast crops? I had great sucssess doing this with asian salads for stir-fries.
Bush beans that love the heat in pots or containers? I had moderate yields, but as I said, started way too late. I did mung, adzuki and kidney beans in the greenhouse just to make use of the remaining space. Planted some outside as well for the experimentation. Much bigger and fatter yields from the greenhouse, here in the UK. I'm just going for mung beans this year. More plants and hopefully a much greater yield for later sprouting and stir-fires.
Maybe fruit trees, if you are inclined? My dad has great sport with citrus and kiwi, although it did take a few years.
Regards
P.S. Why no chillies?