Looking for Next Plane

I am looking for suggestions from the peanut gallery on my step-up aircraft.
I am IFR certified with about 500 hours PIC.

I currently own a 1968 Cherokee 180D. Good, sturdy bird and has served me
well. It's great for sightseeing and taking folks for rides, but slogging
along through extended cross-countries can really take it's toll. The Mrs.
tolerates flying as long as we are going somewhere.

What I am thinking about is something with more speed (who doesn't!) but
still has reasonable maintenance costs. The typical trip for us is around
600 NM, usually just me, the wife and a small dog. She likes to sit in the
back seat (1st row of the First Class section) and spread out her comfort
items. I like her to sit in the back so I can spread out my pilot junk.

I'm not afraid of moving to a complex aircraft, but I'm also not made of
money.

Any suggestions???

Thanks

Mike