What airplane would fill this mission?

You suggested a Zodiac 601, and I'll agree...

Important to Haves:
- could be kept outdoors (eliminates fabric?)

Not a problem. All metal 6061-T6 corrosion resistant construction.

- can carry 2 people

Yes

- could be eligible for sport pilot flight (1232lbs gross)

Yes, depending on model. A 601HD and a 601XL should be.

- could cruise at 95+ kts

Depending on model. My 601HD cruises at 93kts in real-life.
Obviously a 601XL or HDS will go faster.

- could do limited/basic aerobatics

The 601's are designed for +/- 6g's (ultimate, pilot only). Obviously
not an Extra, but you can certainly perform mild aerobatics (loops,
rolls, wingovers, spins, etc) without problems.

- has at least reasonable short/soft field performance (say
1500-2000' grass)

Yes. My 601HD takes off/lands in 1000 ft even at 7000+MSL.

- is relatively cheap to fly (engine 115hp or so, decent TBO,
5-6gph cruise)

I used a Subaru engine. About 5.5gph fuel burn. Total ownership
costs (excluding purchase price but including maintenace, liability
insurance, fuel) run me around $12/hour. Tie-downs/hanger is extra.

- it's not a one-off design that has no parts support or can't be
insured

Zenith aircraft's been selling them since 1984, with over 1000 flying
worldwide.

- if I have to build it, it needs to be "easy" (I've never built
something, a quoted time of ~400hrs maybe?)

Zenith quotes 400 hours. They've built them in 7 days with amateur
labor at Oshkosh and Sun-n-fun. I built mine in 650 hours including a
full instrument panel and some extras.

Nice to Haves:
- side-by-side seating

Yes

- tricycle gear (mostly for insurance)

Both available. I have the taildragger. My insurance is $280/year
for liability. When I was buying hull insurance it was an extra
$1050/year for $35,000 (same was true when I started flying, when my
TT was 160 hrs with 40 hrs in type).

- could be used to teach my Dad to fly (in terms of flying/landing
qualities..I'm thinking sport-pilot-esqe, so I don't know about the
regulations/legalities yet)

Very docile plane, even the taildragger. I test flew mine having
never been in a Zodiac before, or flown a low-wing plane.

- I'm partial to high-wing, just because of the view down, rather
than the view up.

The view in a Zodiac with it's canopy is so spectacular you'll never
notice that you have to bank to see straight down.

- Is a type-certificated airplane (I am seriously considering a
homebuilt, but would prefer something that I could be flying sooner
rather than later)

Building will clearly take longer than buying... but you'll know the
airplane much better and you'll be able to do the maintenace and
annuals (which can save a lot of money). And then you'll have a
brand-new plane. Build times for Zodiacs range from the 7 days quoted
above to, well, as long as you want to take. I built rather
leisurely (averaged 53 minutes/day) so mine took 2 years.

- could have gyros/ifr certified? This is very low priority, but if
it could not be grounded by "benign" ifr, that would be a bonus

An appropriately equipped Zodiac could be used to "break through" a
ground layer to VFR on top, but would not make an acceptable "hard"
IFR platform. It is simply not stable enough (when you design a plane
you make a tradeoff of stablility for responsiveness - the Zodiac,
being a sport plane, is more nimble than stable.) [Note that I am not
instrument rated, and thus not an expert on what would make an good
IFR platform]

My 601HD with Stratus Subaru, full instruments, NAV/COM & XPDR cost
about $31,000 total.

-Bruce

**********************************
Bruce Bockius
http://www.WhiteAntelopeSoftware.com/zodiac