1. I think if you take the offer to upgrade you’re SPG Personal to the SPG Lux, you should be able to continue using your Personal card until you receive the Lux, which would allow you to put those decent sized expenses on your card now rather than waiting for Monday.
Supporting this is the fact that the SPG Lux is supposed to give you Platinum status if you spend $75k on it a year, and if you upgrade your SPG Personal all spend on that card this year is supposed to count towards the $75k.
I would probably check your Amex account after accepting the upgrade offer to see that it’s been updated to reflect a SPG Lux account, and confirm via chat that you can keep using the SPG Personal card until you receive the Lux and that ongoing spend on the Personal counts towards the upgrade bonus.
This may have been discussed on r/churning but I haven’t had much time to catch up there today.
2. Agreed with
@tink1970 - consider if you can really make the $15k spend that you’re estimating (I’m guessing between the BGR and SPG Lux). It’d be a shame if you miss out on the 100k Marriott points bonus. The SPG Lux card is a $450 AF (I’m assuming you’ll basically be charged that upon upgrading) that’s offset by a $300 Marriott credit. Everything else, the Biz Plat you want to get also offers (SPG/Marriott Gold Elite status, PP Lounge, GE/PreCheck). So if you don’t get the 100k Marriott points, you’ll be essentially prepaying $300 to Amex for a paid Marriott stay in the next year, and maybe you can get GE/PreCheck for one of your girls. There’s certainly value in the 50k FN certificate, but the terms say it’ll be deposited to your Marriott account 8-12 weeks after your anniversary and your card needs to be open at the time. I haven’t seen any DPs how soon after the card’s anniversary these certs are being deposited, and I’m not up to speed on Amex’s policy of refunding or prorating AF after cancelation and how long you have to do it, but that’s something to consider about when thinking about canceling.
3. With at least three DISers reporting the no welcome bonus warning, I’m feeling very cautious around Amex now. I don’t think number or velocity of card openings matters as much as putting regular spend on your cards, but clearly how many cards you’ve opened is a factor because the warning expressly mentions history, including the number of cards you’ve opened and closed. Even if number of cards opened may not weigh as heavily in Amex’s anti-churning formula, as a practical matter the more Amex cards I open the more I’m going to have to spread out my spend to keep those cards and my relationship with Amex in good standing, and the more I’ll eventually have to decide to close.
Earlier this morning, I would’ve suggested what most of r/churning probably would’ve said, use your SPG Personal to self refer yourself for the SPG Lux, get approved for the 100k and pocket another 20k referral bonus. Then take the upgrade offer on the SPG Personal > Lux for another 100k. But if you value your relationship with Amex, and want to go back for a Plat in a few months, I probably would opt taking the upgrade offer if I wanted the SPG Lux rather than opening another card.
And like you said, it doesn’t take up another */24 slot.
(Personally, I did not receive an upgrade offer on my SPG Lux, so that was not even an option. I have been hitting Amex pretty hard this year and have decided to put off applying for the BGR until next year to give myself some time to cool off, put some spend on my Amexes, and try to make use of Amex Offers and bonus categories.)
hahaha
And then the United card near the first of the year (just the regular one, not the Club one with the $450 af lol)
After I got the popup for the Aspire, I thought, "What the heck, my credit is unlocked until the end of the month, since I'm not getting the Aspire, I may as well apply for another card." Applied for the Citi Premier with the 60k bonus. DENIED. 
).
. Guess I'll need to check and see how much more they took from my ED and BCP...
piling on the MSRs...
