Does anyone have a link to a map showing the layout of the terminals at Heathrow, including the covered walkways connecting the terminals?

I've never seen a map showing the routes between terminals - you just follow the signs

For maps of the terminals go to the Heathrow Airport website and click on "terminal map" on the home page quicklinks

No, and I've searched and searched for a map of the tunnels one traverses as well. Yet another of BAA's charming customer-friendly operation.

Is this one any use to you
http://www.bedsearcher.co.uk/airport...airport_uk.htm

The Bedsearcher site doesn't show walkways, and isn't to scale.

This one does show the walkway between terminals 1, 2, 3 and the central bus/tube/railway cluster: http://tinyurl.com/29bov9 Apart from the landside corridor between T1 and T2, and the separate airside link between the two, there are no other linking walkways: T4 and 5 are accessible only by road, tube or train

It's not meticulously detailed: it doesn't show the separarate arrivals and departures exits at T3, or the various staircases off to the bus station, the tube and the railway station in the middle. But at least it's a start.

However, in fairness to BAA, Heathrow is a hugely complicated place and it's understandable there isn't a 3D mockup on the web of every drain and staff locker. You might get better information quicker by just posting a question about - say - how easy it is to get luggage from T1 to T3 departures.

<<< how easy it is to get luggage from T1 to T3 departures >>>

Load luggage onto free trolley, follow the signs - it's as simple as that.

Only when T4 & T5 are involved does it become painful but (once T5 opens) the rule is

for T4 - follow signs to Heathrow Express / Heathrow Connect & get on the FREE between terminals Heathrow Connect. The next stop should be the rigth terminal unless you've got on a train to Paddington

for T5 - it's the same as for T4 except you get on the Heathrow Express.

Between T4 & T5 it won't be very pleasant as it involves taking the HEC or HEX (depending on the starting terminal), getting off at the next stop (see earlier warning) then taking the train that isn't the one you've just got off to the other terminal

If you are transferring airside then you will only have hand luggage so all you do is follow the signs to "Flight Connections Centre" and let the staff guide you

What I'm after is the easiest way to get from Terminal 3 to Terminal 4/Hilton Hotel. Somewhere I read that there's a covered walkway between T3 and T4.

<<< Somewhere I read that there's a covered walkway between T3 and T4. >>>

No - the 2 terminals have a runway & several taxiways between them

Simplest (well only really) if LANDSIDE is to follow the signs to Heathrow Express and take it between the terminals - BUT if T5 has opened you take the Heathrow Connect between terminals

If airside, follow the signs to "Flight Connections Centre" then do as you are told

I can see that this will be a real challenge.

T-4 is a loooong way from T-1, 2, 3

If you are using T-3, many of the off-airport hotels will be closer/more convenient than the Hilton at T-4.

We'd actuallylike to stay at the Marriott, but that again raises the issue of whether a taxi driver would take us a fairly short distance. Avoiding the Hoppa bus seems to be a wise idea.

I personally don't understand all the angst on Fodors about the Hoppa. Is it a bargain - absolutely no. But it is pretty straightforward - get on the bus w/ the route that includes your hotel, and get off at the hotel.

However, cabs will take you to the off airport hotels, so that is probably what you'll want to do.

My "angst" about the Hoppa is (a) it is no bargain - what an understatement; (b) the pickup points, esp. the T1 smoke filled tunnel, are horrible; (c) maybe it's my bad luck, but "my" Hoppa is inevitably the last one to come by; (d) on bad-weather early mornings more than once I've had the Hoppa arrive at the hotel too full to allow boarding pax; (e) the luggage racks are full and there's no place to stand or sit; (f) customer service is an oxymoron; (g) it doesn't go to T4, necessitating double the transit time to/from hotel and terminal; and (h) it's a stupid name. Hoppa bus. Cuppa. Drinka pinta milka day.

Other than that, it's a luverly introduction to Britain for many thousands of strangers. Not.