Need advice on what time to take the train from Paddington Sta. to make a 7:35 a.m. flight from Heathrow. Also, we arrive in London about 1 p.m. Thurs. and have to take the flight at 7:35 a.m. Fri.
Is it crazy to stay in London or should we stay at Heathrow? Staying in London is our preference, since it gives us more time to sightsee. From what I've read, it takes about the same amount of time on HEX as it does from an airport hotel. Thanks.

May I ask how you are getting to Paddington and from where? My experience has been that you can get a car service (think Just Airports, for example) that will pick you up whenever you want at your hotel and deliver you to Heathrow in about the same amount of time as the usual trip to Paddington (unless you're staying across the street) plus the Express, and the car service will probably cost less than a taxi and two tickets on the Express.

What time do you have to be AT the airport according to your airline? I'd allow one hour in the wee hours of the morning from my door in Central London to Heathrow.

I usually recommend staying in central London when one has a full day's layover like this. But when the departure is very early in the morning it is probably better to stay near the airport.

No matter which mode of transport you use - from a London hotel to LHR will take you 35 to 60 minutes. Since you have to check in early you are talking about having to get up by about 4 a.m.

If it were me, I'd check into a LHR hotel (great rates using Priceline) Thurs afternoon and dump the luggage. Then head into London for the afternoon/evening, and then head back to the airport hotel for a good night's sleep.

Meant to add - in your case, staying in central London won't really give you much more time to sightsee. You can't do much sightseeing at 5 a.m.

Thanks, Patrick and Janis. Don't have a hotel in London yet. I had planned to stay Mayfair or Kensington or even Bayswater, as close as possible to Paddington. I was thinking that we'd have a few extra hours to be in London in the evening but maybe it would make sense to just take a cab out to LHR in the evening and stay there. We'll be exhausted by 6 or 7 in the evening for sure and it would be nice to have dinner in London and then collapse at our hotel there instead of dealing with finding our way back to a hotel at LHR.
My thinking is that it could take 20-30 min. to get from an inconveniently located hotel at LHR, so we'd only be saving 20-30 min., although getting up at 4:30 is 30 min. better than getting up at 4.
Also, how risky is it doing Priceline for a hotel at LHR? Thoughts?

I'd advise staying at LHR and taking the Heathrow Express to Paddington, from there you can walk or take the Tube anywhere in central London. I can't remember how late the Express runs but you could also take the tube back to LHR, not a bad trip when there's no luggage involved.

One other possibility: if you sleep in a hotel within a few minutes' walk of Paddington, you can get to your plane in about the same time as staying at the airport. The Hilton on Praed Street comes to mind - it's a short walk to the HX.