there are 2 'parts' to this discussion
1) Do I want CB or points
Doing MS for CB will have a poor ROI when compared to miles/points, especially when you add in new credit card applications. It seems like you & your wife are pretty vanilla, you have a plethora of CC bonuses to exploit.
CB will yield, what, 4% average at most in a year? You do 15k a month average, that's $7,200 CB at the end of the year off 180k run through CCs
2 years ago, I started running $30k a month through CCs with the vanilla reload cards (long since dead) and amazon payments (also dead). That would have most likely netted me somewhere around $10k cash after MS expenses.
However, I used that MS to pump and dump various credit cards and it got my wife & I:
1) a trip to cancun in business + weekend stay at Westin for taxes only
2) a 4 day trip to Conrad in Maldives at an OWB in TK Business + activities and dinners at the resort for $4k total
2) 4 days in Bora Bora + 4 days in Moorea @ Hilton properties, upgraded to OWB for free, plus flights USA - PPT - USA, plus internal island flights at PPT, plus a bunch of activities, for under $2k
Just the Maldives trip should have cost somewhere around $20k from my most frugal calculations, so that alone was worth more than the CB
I MS for points/miles which I have learned to exploit like crazy
-----------------------------
2) Do I want to churn CCs?
If you DO NOT churn CCs, then this game is pretty much worthless for you.
Last year with the CITI AA EXEC MC my family pooled around 1.6 million AA miles, which includes the 2x1 CITI AA PLAT cards that we were gettign every 8 days.
That's a lot of miles!!
Aside from that, a lot of people focus on 401k/ROTH IRAs for retirement. Few people look at LIFETIME status with HOTELS/AIRLINES as part of the retirement package.
SPG, for instance, will give you lifetime gold for 5 years of gold + 250 nights. Reward nights count towards this. The AMEX SPG pers+Biz will give you 5 nights each a year, so 10 nights total. If you pump $30k through either of the cards, you get gold for that year. Do this 5 years in a row and you've gotten 50 nights + satisfied one of the criteria for lifetime status
If you and your wife do this, then each has lifetime status, which means better rooms, free wifi, and sometimes club access that has free food & drinks. This might not be a 'spectacular' benefit, but when you travel with family, it brings down the costs dramatically.