Simply put, stay away from a sea pro, they have not had the best rep for quality, and everyone I know who owns them says they fall apart quickly.
As for the Robalo vs Grady, both are well built and quality boats. The gulfstream has more cockpit space and is built more for fishing. The wide beam is nice, adding more interior space making it feel much larger then it is. The cabin is IMHO not the best layout, but it works. It is not overly huge, but it does sleep two, it will not have the thrills inside others may. The Grady has a walkaround, it eats up space in the cabin but will provide safe passage forward.
The robalo is a nicer looking boat but has less cockpit space by far, it is more suited for cabin use. The cabin is much nicer appointed and since the Robalo does not have a walk around, but a flush deck it has more room inside.
Also note, the 23 gulfstream is more boat then a 24 Robalo, the robalo's overall length includes the euro transom which cuts deeply into cockpit space, you are really buying a 21-22' boat with a big transom. The Gulfstream gives you a 23ft boat with less of a transom since it has a bracket, it is a true 23' boat, minus maybe a 1.5ft for the transom and seat aft.
To decide what is best for you, you need to figure out your main usage. Are you going to fish or cruise more. If you fish, the cockpit is a big concern and space is valuable, if you will be cruising more, creature comforts and looks may appeal more. If you compare fuel and fishwells, they are similar enough to make them neglegible in deciding. If you fish, consider what gear you use and how you fish, a bracket is not easy to fish around, but you can get close to the transom on the gulfstream, except for the bracket itself nothing is in your way. The Robalo has a eurotransom, placing the engines far back from where every you fish making it a little tougher. The eurotransom does make boarding a little easier, you could opt for a full boarding ladder for the gulfstream, but that makes both equal in fishability from the transom. Decide how many you will fish, IMHO the Robalo will fish 2 in comfort, and 3 would be my recommeneded max. The gulfstream will fish 3 in comfort, and 4 max. I know you can get more in the cockpit, but if you really fish you do not want more then that. If you will be fishing with more, consider the bow are to add another angler, the gulfstream makes it easier to pass up front and fish, with gear and such, going forward on a flush deck is not always easy, my 265 express has flush decks and although I do not go forward much, it can be a pain at times. If you plan to cruise, this all may not matter as much. If you are looking to entertain, decide which will seat as many as you plan to have in comfort, how many may want to be in the sun, as well as around the helm. Will you have deck chairs and a table out, more space is valuable then to fit it and allow you to still walk by without everyone moving for you.
Both boats have a good resale value, the Grady will hold its a little better then the Robalo, but Robalo's do hold their value better then most in the market.
I'm assuming most will be similarly powered, compare fuel burns and speeds to see what may suit you and your needs best. With the price of fuel, efficiency may be a big deciding factor. Also take a peak at the helm, decide what helm guage layout is easy on the eyes and will make you feel comfortable operating. Make sure the line of sight is clear and you can see all of the boat from the helm. Check the windsheild height, if the frame blocks your sight, you will need to do something to change that or that is not an ideal situation. If the windshield is below your eye level, you may not want to run without drop curtains, the wind will always be in your eyes when running. Ideally you want one that is above eye level or at eye level at the least, I know not all boats are this way, mine is not and is one down side but in the NE I do not need to open all my curtains as much as you may want to in Fla. Check and see which boat will offer you enough space to mount electronics as you may want them, make sure they have enough space and that you will not be breaking your neck to see or reach them. If it is just you and your wife, you will want her to be happy, check out the Grady and the Robalo in the same day if possible, and list the positives and negatives of each model, and see what one suits you best. Your wife may like the comfort of the Robalo, but not walking up front to help with lines since there is no walkaround, that is something she needs to decide, after all I'm sure she has a big part in signing on the dotted line.
Hopefully this helps and gives you ideas to think about. Good luck in the decision, let us know what you decide.