Seeing flights for May (near Memorial Day) for $230-260 for most carriers.
Non stop, staying over a Sat, 7 days plus.
Realize the holiday bumps it up.

Is this a good fare rate?

Yes. I keep getting notices (since I've entered it in my profile) from AA for RSW to ORD round trip specials, and sometimes they go a little under $200, but I see for the dates I entered at the end of May, they're doing $234 ($250 with taxes). I'd go for it and pick good seats now.

My folks fly this route regularly, and they scored a $138 fare on AA about three-four weeks ago for a February vacation. While your $230 is a decent rate, you would probably be safe in waiting for American's next fare sale, probably posted in late January. I assume you know that Sarasota, Tampa or Orlando are reasonable alternatives for visitors - you can sometimes fly into one airport and out of another for the low round-trip fare. Jet Blue and Southwest have not released their tickets for those dates, so I think you are better off waiting.

I'm tempted to agree with patg, and looking back I see that we paid under $150 round trip on Amrican with taxes last time on such a fare sale, but one issue is that you are talking about over Memorial Day. Usually when those fare sales are released, there is little or no availability (or blacked out) for times over that weekend. Perhaps if you can go Wednesday to Wednesday or something you might be able to get a great fare.

And I do see that internet one way fares total for the round trip about $135 with Southwest even for the nonstops.

I would think if you keep tabs you could do better than that for that season.

It seemed a bit high to me also.
I usually travel that time of year (over Memorial Day) and recall getting better prices than that but I have usually been headed to Key West via Fort Lauderdale or Miami.