Smala01
Good to hear you had a pleasent experience. I´ve had some decent layovers in Doha as well as some terrible ones (I suppose it depends on the time of day- 6 hours through the night when tired is never too much fun).
Check out the Museum of Islamic art. Building designed by I M Pei.
That would be my reccomendation for future reference. Anyone with a western passport can buy a visa on arrival (I think its $20- and you can only pay in dollars or by credit card) and spend a few hours exploring the city (or getting a tan!).
I would say its a definite NO to accept a 30min transfer in DOH
In the case of a DOH-DUB transfer, I dont think it really matters. QR flights to Dubai depart almost hourly, 24 hours a day so if the worst happens, you wont be waiting too long to get on the next available flight. In any case QR are (in my experience) quite good with regards to connections- I´ve had a few upgrades and free lounge access when I´ve missed long haul connections but it hasnt happened often.
Anansis