One of my DSs loves sandwiches, so most days he has one, but he has to choose between toast for brekkie or sandwich for lunch so he doesn't have too much bread in a day.
Same as in our household...thye only get bread once a day.

With DS I find it very hard to alternate his foods. He is such a fussy eater much to my disgust, and most days (if I let him!) would be happy with vegemite sandwiches all day, or vegemite on rice cakes. Both kids had toast this morning for breakfast so lunch will be what I call a "tasting plate" - usually consists of hard boiled eggs, red capsicum, cheese, ham, mixed beans (the 4 bean mix type), maybe a rice cake. If I am lucky DS will eat the egg, the ham and cheese whereas DD will eat everything and whats left on her brothers plate!