relay logic

Anyone have intermediate to advanced level advice on relay logic? When I was a kid, each relay would cost about one hour of labor, a cheap bench linear supply could only handle about 10 active relays, and fanout ratios were maybe only 5 to 1. Now according to my latest Mouser catalog, each relay will cost me about two minutes of labor, a cheap switching power supply will run hundreds of relays, and I can easily get a 10 to 1 fanout even with cheapie relays. I'm quite well aware of how to make basic gates, FF, counters etc out of relays but I'm curious about anyone elses experiences. I can contemplate all kinds of weird problems like mechanical shock from so many relays clicking at once, or the relay equivalent of contact bounce, but I don't know if they're real problems. Then there's mounting issues.