broiled tomato question - and fancy salt & tomatoes ???

In another thread, Larkie said "I have always eaten tomato slices topped with mayo & cheese.. Top a slice with the mayo, salt, pepper and grated cheese and broil"

I'd like to try this. I am wondering what type of cheese would be best to use? I ***finally**** have some tomatoes getting ripe, and am looking for some new things to try. This sounds so simple and good. I just started eating tomatoes a few years back, and am really enjoying the heirlooms I have been growing the last couple years.

I have on hand Asiago, Provalone, Swiss, Co-Jack, Black Diamond Cheddar, Sharp Cheddar, and White American. Am hoping one of those will work?
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Next question...

Salt really does make a difference to a fresh tomato slice.

Am considering buying some special salt to try with tomatoes. I normally buy Sea Salt at the grocery, but noticed the health food store I go to has a pink salt and also a "grey salt". I am considering buying one of these special salts just for using on tomatoes. One of my favorite Food Network chefs, Michael Chiarello (sp?) uses gray salt all the time... but I think it was $9 for 6 oz. They gray salt was already course ground, but the pink is in chunks to be fresh ground in a grinder. They had it packaged with a grinder, and also had packages of "refills." I don't remember the specific price on the pink salt, but it was about half the price of the gray salt.

Does anyone use a fancy salt on their tomatoes and do you think it is worth the $$$$$$$$ ??

Is it especially good on anything else? Would it keep well if I store it in a dry place until next year's tomato season?