Purchase Upgrades?
 

Does KLM offer the option to purchase upgrades at check-in?

They will send you to the ticketing office for three possibilities:
1) upgrade your fare to business class (provided fare rules of the original ticket allow that)
2) upgrade your fare to fare class B with a fixed fee per fare class AND pay mileage to upgrade to business cabin (not for V-class, not for AF flights)
3) upgrade with miles to business cabin (S/B fare code only on KL)
--> 1) possible if seats for sale in availability display 2/3) possible if any spare seats in the flight load but subject to approval of flight supervisor.

Alternatively you can swipe your credit card onboard for an onboard upgrade.
But note that comes at a very hefty fee (usually much more expensive than option 1)

It looks like my outbound segments are Q (QLUSE), and inbound are B (BLEPX). There are a couple rail segments, and an AMS/CDG/AMS internal trip (both directions B), but the ones I'm most concerned about are the trans-Atlantic (ORD/AMS/ORD) segments.

All segments are KLM.

For your outbound flights you could then use option 1) or 2)
For your inbound flights option 3) would do,
Both of course only if sufficient seats available.
Good luck!

P.S. Love to use miles, but I don't have any, as this is my first KLM trip, and don't have any other Skyteam cards.

<<Edited out stupid question>>

It never hurts to ask - but good deals are often only available from obscure airports where they have special fares for the local market (e.g. some African and Asian countries).

Open a Flying Blue account. Transfer points from SPG to Flying Blue (takes about a week) and with 20K Starpoints, you got your 25K Flying Blue miles for a one-way upgrade between North America and Europe.

Neat idea. Sadly, I don't have enough SPG points available right now, plus I don't have the week to do the transfer, as I'm flying out on Sunday.

In that event, odds are very high that you'll have to stick with coach unless you want to pay up to the applicable business class fare.

As your chances of getting an upgrade (unless you pay for it) are close, if not equal to zero, I'd suggest you buy some nice flowers and offer them to the check-in agent when asking. If (s)he is of the right sex, it might work...

FWIW, and for some reason, my return flight appears totally (and probably way over) booked. What are the chances of being op-up'ed on a B fare without status? If offered vdb (assuming a re-route resulting in same-day arrival at final destination), what can/should I go for?

I have never actually seen anyone be "offered" VDB. I once offered to volunteer on a flight that appeared to be overbooked, and was told, "We don't do that."

There seems (from other threads) to be some question whether AF and KL follow the European rule about asking for volunteers.