Friend and I arrive from ORD, hopefully within an hour of each other, at Terminal 1 and Terminal 3, then plan to meet up and take tube into London to our hotel ( Millenium Baileys is right next to Gloucester Rd. station on Piccadilly Line).
Trying to make sense of information on Heathrow website and it appears that we should meet up at Terminal 1 ground floor, international arrivals area, opposite info desk and next to London Underground escalator. Do I have this correct? It says the station is located between terminals. Just want to make it as easy as possible.
We already have Oyster cards with funds left from previous trip.
TIA for any info.

Yes. My sister and I did exactly this. I arrived first at T3, and walked over to T1. There's a cafe nearby. Getting to the tube station is very easy too.

I was very pleased with how easy it was.

Given the variables of airline arrivals and length of lines on arrival I think I'd opt for meeting at your hotel where you can wait in comfort.

I'd personally forget about meeting at LHR. Since your hotel is so easy/convenient by tube I'd also plan on meeting at the hotel. Whoever arrives first can either check in or drop her bag if the room is not ready. Then a quick walk around the neighborhood or a coffee/pastry and return to greet the other when she arrives.

Thanks for the replies. Common sense rules!

I'd meet at the hotel too. You can either meet up in the lobby or at a nearby cafe. There is a Paul right across the street for the hotel also a Pret a Manger or a bar right in the hotel!Good choice I always stay at either Baileys or Next door at the Mill. Gloucester they are so convenient!!

If you do still want to meet up at LHR, I'd suggest meeting in the seating area of Heathrow's Central Bus Station there, which is near a Tube entrance and is a well-marked walk from the terminals. There are places to get a sandwich and a newspaper and sit down, and the seating area is not so big that you'd miss each other.