Icaridin (a.k.a. "picaridin") comes out well in head-to-head comparisons against DEET, and it's CDC-approved. When I've been lucky enough to buy it I've found it easier on the skin than DEET.

Heat works for me for itchy bites, although maybe it's a placebo. In any case, here's what I do: boil/microwave a cup of water; put a spoon in it briefly; dry the spoon; let it cool just enough so it won't burn me; press it against the bite for a few seconds. The itching intensifies while I apply the heat, then subsides to less than it was before, and stays low for an hour or two.

There's also a commercial product called After Bite that might work if you apply it soon after you're bitten. However, it's basically just a 3.5% ammonia emulsion with a special applicator, so you might as well buy plain ammonia and dilute & apply it as necessary.