1) Field mushrooms, tarragon, bit of celery (as much for texture as for flavour).
2) Assorted pulses (lentils, beans, WHY) baby turnips, savoury and/or thyme.
As a general idea, not too many differing flavours, let each show itself properly. To increase variety I would suggest sometimes dropping the tomatoes (I feel they tend to take over the dish) and replace with stock, or a thin soup.
At serving time adding a good-size spoon of yoghurt (not really stirred in) or a sprinkle of paprika, can buck things up a bit without too much drama. They can also be omitted if you have an individual diner who prefers things very plain. Likewise a dish of fresh-grated parmesan for those that will.