Without knowing your departure time, your tolerance of Indian train journeys and your ability to get yourself from the station to the airport at a sensible price, its hard to give this advice.
On a cost basis it is no contest, we recently paid just over Rs900 return to Bombay - for two.
But to be honest, most people who consider the train as part of the actual journey, rather than a separate trip end up opting for the vasly more expensive plane, simply on the grounds of simplicity.
I am amazed that you have 11 hrs at the airport who is that with?
(And I hope it was very cheap to compensate!)

we took the train from mumbai to goa because we wanted the experience we travelled during the day , so we could see the scenery etc... when we looked into booking trains left mumbai at 7am and 7pm and the journey takes approx 12 / 13 hours , we booked 2nd class A/C we got a pillow , clean sheets and a blanket , snacks and meals were available through out the journey , we have done the trip twice and also taken the train from goa to kerrala and would recommend it

We are going with Etihad land at 2.20am in Mumbai so that's the reason for the long wait I believe the connecting flights don't start till later in the mornig The price wasn't dirt cheap but wasn't too bad 440 or so each as we are in Goa for 3 week and then down to Kerela for 2 weeks - we fly directly back from Kerela 1 stop in Abu Dabi but you don't mess with your cases as Etihad check them right through to Manchester.
(well they did last year)
Well being in the prime of life (64 and 66) we fancy a bit of excitement so i think it may be puff puff here we come.

Carol, I priced Etihad as well as their prices were quite competitive. Are they ok to fly with? (sorry a bit off topic I know)

Brill!! I know it can be a bit of a bind changing but flying with them is like flying with First Choice Premiumn.
We had a choice of meal, proper knives and forks etc and the in flight entertainment wasn't too bad. And better still for my other half drinks FREE - you just have to ask

Thanks Carol. Good to know for future reference

Hi carol there is another option book a hotel room near the airport for the stopover,Im sure I have read on here thats what a lot of travellers do slan(cheers)

I think there are flghts to Goa with Indian Airlines at 05:20 and Jet at 06:35.

Dave

The train is an absoloute must do experience, It was one of my highlights, but may not be so much fun after a long flight to Mumbai. We did an overnight sleeper, but from Goa to Mumbai and was for a few days stay, if I have a long stopover I usually book a hotel, and they generally transport you to and from the hotels,

I agree with Lin b the train is a super experience, we went last year in Nov, you see a lot of the countryside (thats if you travel by day),and you can enjoy the different people that board the train selling all manner of things from food ,fruit to toys all at cheap prices.We also encountered the famous transvestite group that say a curse on you if you don't contibute to them all in all a great experience.

Qatar Airlines will fly direct from Manchester to Goa from November this year. There's a stop at Doha but the times between flights are quite good.

I think Kingfisher's first flight is about 5-00am.

Indian Trains are fantastic, a great way to travel, I have done Mumbai to Goa twice once in 2nd class A/C which was lovely but a bit remote from the real feel of the train and the second time 2nd class non a/c, you get more of a feel for india. I have also done Goa to Delhi 42 hrs !! bit long but very cheap.