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Thanks for the suggested alternatives, Robert. Wd 1 requires high-elevation, dry, Southern skies as remote from light pollution as possible. It's a challenge object more than a delight to the eye. Your suggested alternates are good ones. NGC 3603 is an easy star-hop cluster and the densest stellar agglomeration I know of available to amateur-sized instruments. Nearby Westerlund 2 is just as dense and has a similar-looking nebular ring (obscured by dust in some quadrants), but 3603 outshines Wd 2 by a good two mags at the eyepiece. It is one of those clusters at which you can throw all the magnification you have and it just gets better. On a good night my sharpest optic goes to 400x and yields up more and more glitter as I max out my eyepiece collection.
Trumpler 14 also is easily overlooked, in this case by nearby Eta Carinae and that whole glowing gas assembly around it. There are seven infant OCs in the wedge of HII which has Eta near its tip. Tr 14 and its surroundings are Exhibit A for the case that giant molecular clouds fragment as they collapse, leading to closely-sequenced OC mass assembly just beginning to expel its clouds of natal gas.
Re M11, agreed that it is such a popular object that its prettiness sometimes overshadows its place in the OC/GC scheme of things. It's definitely understudied in the recent literature. In eyepiece appearance it mimics a very nearby Class X or XI GC, but a lit search shows its metallicity to be 0.11. Its age of about 200 million years is past the mass segregation phase. I couldn't find any info on its stellar mass loss rate or halo luminosity, but the fact that M11 can hold on to so much stellar density at its present core concentration argues well for its being a GC candidate. M11 has a triple main sequence in the UBV and VIc colour bands and shows no sign of a blue HB. That would tie it with NGC 6808 for being the only old cluster with a three-generation ancestry. But what the heck, anything as pretty as M11 doesn't really have to be thought of anything but itself. It rises at around midnight these days and is glorious by 02:00. What more could we ask for?
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