If it were me,
I'd go for a 6" newtonian on an EQ mount. Something like the following:
http://www.ozscopes.com.au/skywatche...telescope.html
It would serve you for years to come.
A 6" aperture is still a decent size scope and it will show you plenty the night sky has to offer. Realistically also you won't be getting any extra usable magnification out of a bigger scope, just makes the dimmer objects easier to see just that bit more.
It would be very easy to carry to and from the house, or if you wanted to transport it also.
The deal breaker for me would be the slow motion control knobs on the EQ mount as opposed to having to manually nudge and push the dobsonian mounted scope. Especially if you're using higher magnifications on the planets the nudging and pushing would become quite average as opposed to having slow motion knobs to finely track the object in the eyepiece.
And if he decided to upgrade later, he can buy that large aperture scope, say 10" or 12" to dedicate to it more, and still keep the 6" as a second scope. But I'd suggest to get the GoTo tracking on a later upgrade to get rid of the manual movement on the scope to keep things centered so you spend more time viewing than moving.
But as for getting the most aperture for your money, you can't beat the dobsonians.