Most yoke regs are usually limited to 3300 psi or less.
Tanks with a service pressure under 3500 psi can use a 232 bar DIN/K manifold that can be used with either DIN regulators or yoke regulators by screwing the inserts in or out. This is a good option if you do not want to convert your regs to DIN (yet). They use a 5 thread DIN valve connection and longer 7 thread 300 BAR DIN regs can be connected to them.
300 BAR DIN manifolds are used for tanks with service pressures over 3442 psi although many divers with DIN regs and low pressure tanks opt for 300 BAR manifolds anyway, just to keep their options open if they acquire high pressure tanks later. These use the longer 7 thread connection and a regulator with a 232 BAR 5 thread connection will not seal in them. This prevents regulators certified for lowere service pressures from being connected to high pressure tanks (up to 300 BAR/4350 psi).
Thermo brand manifolds are popular and cost a bit more than some of the others (around $225-240). Personally I am of a fan of the Scubatek made manifolds that are sold under a variety of names such as Halcyon, AGIR Brokk, DIR-Zone, and Sea Elite. The valves close in about a half turn less than the valves on Thermo manifolds and the qaulity is just as good (in my opinion - Thermo fans may disagree).
Most of the current manifolds are modular systems using valves on each tank that can be connected to a cross bar or isolator valve or can be plugged and used as single tanks. The cross bars and isolator valves are designed so that the lenght from center to center can be adjusted to accommodate tanks of different diameters.
In my opinion the isolator valve is worth having as it allows you to isolate one tank from the other in the event of a failure such as a failed neck o-ring or a failed burst disc that would otherwise result in the loss of gas from both tanks.
Most of the current crop of manifolds are also intended for use with two regulators, one on a post above each tank. You could probably still get a manifold designed for a single regulator, but it would be a bit of a dinosaur and you'd lose the advantages and flexibility of the modular system. And good luck selling it later if you decide you don't want it.
AL100's are fine for doubles, but they are a bit heavy when paired up. My favorite 100 cu ft tank is the PST E7-100 which offers 100 cu feet at 3442 psi in a package no bigger or heavier than an AL 80. At 3000 psi they still offer 90 cu ft and at 2640 psi they have 80 cu ft, so they are still a viable tank even if you are in a location where air over 3000 psi is unobtainable. They are however expensive and hard to find.
