I've had a few 6 hour layovers at SVO. The airport really isn't very nice for long layovers. I looked into the concourse E hotel mentioned above, it is quite expensive, and I guess not very nice.
In some of the terminals there is basically no space, and even finding a seat can be hard. The last time I flew through SVO, I spent about 5 hours at a coffee shop.
The food is quite bad at SVO, as well.
But Aeroflot is cheap, it is generally how I get from Asia to Europe.