I got an Isspro meter from Moyer Marine, mostly because I've been slowly replacing my other gauges from that source and wanted them to match. Also because I drive right past the Isspro factory in north Portland sometimes, and there's a bit of local connection.
The gauge failed in the first few months, and Don sent a replacement right away. He did double-check with the factory and verified that it's supposed to be weatherproof.
I put it in the cockpit, with all the pros & cons listed above. I think it does have a backlight that can be wired to the same switch as the rest of your instruments. I didn't want it to be off by itself somewhere in an odd location, and I wanted it to be handy for recording daily engine hours in the log, and for noting service intervals. (Well, that was the aspiration, anyway.) If I had an aft nav station, as per GrandPa Steve's pic, I might put it there. I guess I could have put it on my nav station control panel, but it would have been a long wire run and wasn't obvious to me at the time. I may re-think this - got some engine-monitor alarm lights to install too...
You can also wire it in various ways. E.g. to the engine key or to the oil pressure switch, or so that the display is always on or only on when the key is on.