Argentina should beat Croatia without Del Potro (only need to beat Karlovic once over the 3 days), but it would be a nice signal of intent if they could count on him for this tie.
He'd also get an early warm-up for the European clay court season, and would have a week to make the trip to Monte Carlo and get adjusted to the conditions over there.
The scheduling shouldn't be a problem for him, as it wouldn't be for the SF either (coming from New York, with a week off before the commencement of the Asian swing).
Since 2006, Argentina has played there all the ties. There is an exception: 2008 final against Spain.It was played in Mar Del Plata(Spain won). Curiosity: Argentina has never lost a tie in Parque Roca.
Mar Del Plata was the most significant home tie for you, unfortunately. And, if you reach the final again this year, and it is another home tie, presumably you cannot rely on Parque Roca in November.