Y’know, if you aren’t opposed to a bridge camera, you can get that kind of functionality without having to switch lenses, although there are clip-on options for macro work that extend the capability. I use two: a Nikon and a Sony. They have different strengths: the Sony has a bigger zoom, and more manual control. On the other hand, Sony buried the macro setting deep in the camera menu. The Nikon is comparatively dumbed-down when it comes to setting flexibility, but the macro button is right there on the back of the body. The Nikon also has a pretty darned good zoom, and its wide-angle lens and bigger aperture means that it’s less fussy about low light conditions.
Both are older models; I haven’t looked at the Sony’s specs, but the Nikon doesn’t automatically record GPS in the metadata. There’s a firmware update available on the website, but I haven’t downloaded it. (Most of the places where I’m shooting, ‘close enough’ is good enough.) This is one of those ‘your mileage may vary’ issues.
I’ve also been doing some research on the Raynox DCR-150 snap-on macro lens, which doesn’t require a bayonet or threaded mount, so it works with zoom lenses. Lots of folks have posted reviews and demo photos, and I’ve been impressed with the results. The 150 is on my summer purchase list; you might be more interested in the 250 for its really up-close capability. (The reviewer at the link also likes the bokeh created by the 250.)
For your purposes, I wouldn’t worry too much about megapixels; a lot of manufacturers are pushing high numbers, but unless you’re going to make large-format prints, a 16mps – that is, 1.6 million pixels – sensor should be adequate. A versatile bridge camera also means no having to carry multiple heavy (and expensive!) lenses. The Canon Powershot series even has a telephoto attachment, but it’s a whole lot more portable (and less expensive) than a DSLR lens.
If you want, you can send me a private message, and I’ll be happy to go into more detail about options.