I've been having salad for breakfast every morning.
Cut up tomatoes get kinda gross in a salad unless you eat it right away. I would suggest using cherry/salad tomatoes so that you don't need to cut them up. (My mom used to put giant pieces of carrot and cut up tomato in her salad... it was so gross, and she didn't believe in throwing out leftovers... so slimey salad day after day... :X )
If you
do want cut up tomato in a salad, I would suggest Roma tomatos and scoop out the center (seeds/liquid), just leave the fleshy part and skin. Most of the slimeyness comes from the liquid.
The same goes with cucumber. Cut your cucumber length wise and scoop out the seeds with a spoon. That'll cut down on extra water content leaking into your salad.