If you spend $30k in one year with the Amex PRG, you get abonus of 15k. So if you put another 5k in gas/groceries/airfare at 2x points that you'd spend anyways, you'd get 50k points at the CC fee of $750 plus additional 5k in spending.

That's 1.5c/point in the best case - not worth it.

If you signed up for 2 Amex SPG offers @ 10k plus 15k after 15k spend (either one personal + business, or one for you and the spouse) and you could split the purchase with two credit cards, you could potentially get 55k SPG points at $750 plus another 5k in spending.

That's 1.4 cents/SPG point, which IMO would be worth it. Or to put it another way, 48k SPG points can put you up at the Westin Times Square for 5 nights which would normally cost $1500.

It'd only be worth it if you stacked the purchase with a new CC signup bonus and needed to meet a minimum spend requirement, or perhaps for the BA companion pass depending on your travel patterns.