I, too, started with Nikon and a 17 inch printer.
Round one with my custom studio storage fit the 17 inch prints/storage just fine. I soon bought a 2nd-hand 24 inch printer and updated the next storage module to handle 24x36...
For the most part, the 24 inch printer was great and the prints superb from the 6-12mp Nikon sensors. I made hundreds of prints on the two printers and paid for both with the large, gorgeous prints and all was well. Then I went to a presentation by Bill Aktinson and his large gallery-wraps.
To me, the writing was on the wall and I could see the potential in my market and doing the wraps and large canvas prints. I went to eBay and bought a 44 inch printer... My only regret is that I wish I had started at the 44 inch printer and had flat storage for larger than 24x36 prints...
Of course, having a larger printer allowed me to create larger prints and canvas and just a couple of jobs paid for the upgrade with the bonus of faster printing with better I.Q.
Now I've got 4 Epson printers... Each works well, but for the most part, the 24 inch sees little action these days...
Because I have a 44 inch printer and have had lots of time perfecting my craft using it, the sky is the limit in my printing capabilities!
Your D700 is capable of fantastic I.Q. and I don't hesitate to make a carefully-crafted image large. Next to my workstation, I have a 30x45 b&w print from a D200, a generation older and lower res than the D700 that is simply stunning--it's even better than what I could have crated shooting my 6x9 architectural camera and film and with much less work to create!
IMO, cry once and spend the money, especially if you have the space. Once you have it, the cost to run it is the same as the 24 inch printer. You can always print smaller with the large printers but can't if you need them larger. For my larges printer, I mainly use 24 inch stock for day-to-day and use 36 inch stock on special occasion. For canvas, I run 24 inch stock for up to 20x30 wraps. Any thing larger goes to the 44 inch stock. Because I can run up to 40x60 and larger canvas prints and I'm the only one in my market, I get the jobs that would normally be taken an hour's drive away, thus saving my clients both time and money and I get the profits. My bonus is that this allows me to print whatever I want just as large and with total control.
I'm in the middle of negotiations to produce 300-400 prints for a client and if they are successful, I'll update to a newer 44 inch prints. If that happens, I'll have both a 24" and 44" that I'll sell you for a good price!;-)