As long as your tanks pass their hydro and visual inspections they are fine. I currently have tanks from the 90’s as well and dive on them constantly. If you just want to replace them, depending on wants/needs/budget you can go with aluminum 80’s again, or spend some more money and go to steel tanks and take some weight out of your weight pockets.
With your wetsuit I’d say it depends on budget, the water you’re diving, etc. For colder water, inland quarries type stuff, the Henderson AquaLock 7mm is a nice choice. It seals well and helps keep water out, and helps keep you more comfortable.
If you’re not diving water that cold, then a standard Henderson, NeoSport, and Body Glove are all good choices. I have dove in them all and gotten excellent use from all of them.