The wife is 5'4". Will a standard plate be OK, or should I be looking at a brand that makes different sizes?
I would say there is a reasonable possibility the "standard" plate would not be the best fit for your wife. I find that it depends not just on height, but also on torso length, i.e is she "short-waisted" or "long-waisted."
I'm 5'5" and I'm very uncomfortable in a "standard" plate (which is usually around 15" or 15-1/2" tall, l believe). But I'm short-waisted, so I'm probably more like 5'3" in Torso Equivalent Height™
When you think about it, it makes sense that the same plate might not fit someone, say, 6' tall and then also someone 8" shorter (not even accounting for potential shorter-proportioned torso).
I found that for me, a 14" plate (for example, Halcyon's Small plate) was better, and a 13" plate was best (DSS Small plate). One nice thing about the DSS Small plate (not sure how others compare; they may be similarly adjusted) is that it's not just a shorter piece of metal; the cam band slots are proportionally spaced as well (but the holes are the standard 11" on-center spacing so you can use any STA if you choose to go that route).
I believe that Halcyon, Oxycheq, DSS, and Agir-Brokk all made at least one smaller-than-standard size as of a little over a year ago. Others may as well.
Blue Sparkle