I dine alone quite often - not only back when I was single, but now that I work and eat out at lunch. I prefer it, I bring a book, and zone out. I've sometimes been seated in the 'gathering', but asked to be sat at least one table away. Usually that's fine.

I've worked serving tables before, and if there is just one person working, having the tables near eachother is preferable for better/faster service. But they needn't be RIGHT next to eachother.

On a somewhat related note, me and two friends were having a quiet dinner, having just gotten our food, at a hotel we were staying at. The three of us were artists, and had just had a tough day at a very hot and sweaty art show with little sales. We were cooling off and winding down. The rest of the hotel restaurant was absolutely empty.

In walks dozens, and I mean dozens of bikers. They were loud, they were rowdy, but they were very interesting to watch The 'leader', I suppose, Old Mick, came up to us, sat down, introduced himself, and said, "I understand you folks were just sitting here having a quiet dinner when we invaded, and I apologize for that. Your tab is settled up, please enjoy and relax as much as you can! Just tip the waitress, and all is set". We thought that was sweet of him, and we did hang around and talk to them a while before we collapsed in our rooms (and yes, we did tip the waitress nicely).