My wife and I took a trip in the convertible last weekend to the local Fry's
Electronics store to get a monitor. While there, we opted to buy a computer
for one of the kids for Christmas. I'm glad we had the 3 Series convertible
because we could not fit the stuff we bought into the trunk.

Buy the 4-seater and use it for weekends. You'll spend about the same money,
but you'll appreciate the extra space. Guarantied. Trust me, the 330
convertible is not a very practical car either, but it is more practical
than the Z3 or the Z4. Frankly, the 325 or 328 convertible (whichever they
sell these days) is as fun to drive as the 330, and it looks damn near
identical. Personally, I prefer the tire package on the 330, but that's just
me.

They are two different cars.  The Z4 is not practical but it will be a
"weekend" car and not an everyday drive.  The 3 series would be my second
choice although there is  not much room in the back seat.  My third choice
would be a X3 but I don't like the expense and maintenance associated with
AWD regardless of the improved handling.

I would get the auto. From test drives, BMW autos seem pretty good to
me. I would suggest staying away from the SMG. I had a 2004 Z4 3.0i with
the SMG and although the technology was cool - I am a bit of a geek and
like that kind of stuff - it was not very smooth shifting. I would say
it is one of the reasons I traded the car in so soon (that along with
troubles with the top and wanting room for more than 2 people). I now
have a 2006 330i with a 6 speed manual and I think it is a much better
automobile all around.

Anybody have a preference of automatic over stick?

I will be buying a Z4.  I want an automatic because 1) I will not be driving
it like a race car and 2) the advances in automatic transmissions make them
as reliable as manuals and 3) I have been driving autos for over 30 years
and am ready for a change.