Lidl do a wholegrain rye crispbread with sesame seeds, It is very light and crunchy. The ryvita dark rye works for me too, but it is thicker and a little harder. For mega thin and very hard, Peter's Yard Artisan swedish crispbread is hard to beat. The high rye content in these brands made them very slow to release their carbs and, unless you are extremely sensitive to any carbs at all, they should be good. As always, test.
I make up 'spreads' by grinding up anyone one of a number of herbs or spices, dill, chilli, mustard seed , paprika, onion seed, chives, etc etc and add it to anyone of a number of things like cream cheese, creme fraiche, sour cream, natural yoghurt, again either as is or mixed. It's great fun experimenting.
A good sharp cheddar, thinly sliced, with very thin slices of pickled onion is hard to beat too.