We each have about 120,000 miles. in planning a European trip this September, would it be better to buy tickets and upgrade to business with the miles or buy tickets with the miles (presume it's difficult at this "late" date

There's no "hard" answer. It depends on the fare you need pay for economy in order to use the miles for upgrade (for example, with CO, you'll need to pay extra + miles for most discount coach fares), whether there are upgrade seats available on the flights you want, and how valuable do you see your miles are worth.

Call the airline and find out all the above, and then decide which is the better way. It all depends...

You don't say what airline you have miles with. It makes a difference. You can upgrade any fare to business class on AA if they have upgrade seats available. On Delta, you have to buy a somewhat more expensive coach fare to be able to upgrade (in summer, usually about $500 more), but they tend to have more upgrade seats available and the upgrade costs you fewer miles than on AA. To me, $500 is worth it anyway because when you use your miles to upgrade, you get the miles for that flight awarded to your account. If you buy the tickets with miles, you get no miles.
Also, in my experience, it is easier to buy a ticket and upgrade it than to buy a ticket with miles, but this may just be an anomaly.

The last time I looked into upgradeable transatlantic fares on Delta, it was much more than a $500 difference compared to the least expensive economy fare at the time. IIRC, it was about $900 more. I agree if it was around $500, it would be worthwhile.

RachelG - Is it "possible" that I "know" you from another website???

Just curious....Thanks in advance....

Best wishes, Dave

Dave,
I lurk around flyertalk some, but usually don't post much there as those people are really the professional flyers.

Last summer, Delta's fare to CDG was $1000 approx (what a paid for each of my kids--not a great deal but ok for mid-summer). I paid $1500 for an ungradable fare for myself and hubby.

I was looking at winter season fares (from LAX), hence the much larger difference.

$1500 - 1700 is about the economy fare you need to pay to be upgradeable for Europe. Haven't looked that closely into Delta, but that's definitely true with Continental. If you get a $700 fare, you'll need to pay $400 each way + miles to upgrade to BusinessFirst. If you get a ~$1000 fare, then it's about $300 each way + miles, etc... Until you get a full "Y" fare.

RachelG - Yes, that's the "site" I was referring to......One of my friends from that site (tho not her FT handle) is named Rachel G. I was just thinking that it may have been the same person,,,,

but the hubby part gave it away!!

Best wishes, and thanks for the reply..
Dave