Instead of trying to find the most sporting H-D, why don't you rent a Road King or similar machine and expose yourself to a completely different style of riding.
You'll find yourself relaxing and enjoying the scenery instead of concentrating on apexes. As a bonus, the touring model H-Ds go better through the corners than you might imagine except for the floorboard scraping which is fun in its own right.
Yup, Road King and then scrape the hell out of the floorboards. You may be surprised how good those bikes corner! If the chassis hasn't change in 10 years then the rake is about 26 degrees, so it can steer tight in parking lots - works for cornering too. Show everyone how good a sportbike rider you are!!
I"ll echo the sentiments above. I got a chance to take a fully loaded Ultra Classic home for a weekend awhile back and I seriously could not stop laughing while I rode the thing. It was a total hoot, handled way better than I imagined it would and was a completely different experience from my Duc. The only thing that really bothered me was the braking, but once I started using four fingers instead of two it wasn't so bad.
Forget the canyon carving. This is a corporate retreat not a squid-fest, Smitty.
Get something with a comfortable looking pillion like a Road King or Heritage and take full advantage of this being the only corporate sanctioned opportunity you're ever gonna have to get all of the secretaries and admins you've been covertly lusting after wrapping their arms around your chest and their thighs around your hips for a day.
Please see my magnum opus on this subject, "A Tourer's Tale" for more explicit instructions.
Sheeesh! I swear, sometimes I wonder what you tech wanking dorks would do without me?!
I had a similar situation about 8 years ago. Stuck in CA (from Boston area) for a long weekend. As a lifelong motocrosser turned sportbiker, I had never ridden a Harley or any such big tourer-cruiser thing for more then a mile or two. So I took the plunge and rented the big Heritage Classic. I figured if I was going to try the Harley experience I'd go all the way. Three full days down the coast from San Francisco. Got to know the bike (at first kept trying to rev the thing - dumb sportbiker I was). Bottom line: enjoyed a different riding experience, got a sense how the other half live, glad I did it, was REALLY glad to get home and get out the GSXR.
So, get the biggest, most traditional one you can get and have fun.
I'm starting to detect a trend here- I'd say try something new and get a Road King.
I was in a similar situation when I had a day to myself on my last business trip to San Francisco. I don't get to see many curves where I live so I was really looking forward to having a good corner carver to ride while there. I looked for a sport bike of sorts to rent and couldn't find one (mostly I wanted a Buell or a ride on the new BMW R1200GS but neither were to be found). Time was short and Eaglerider was easy to work through so I opted for an HD Road King. I''d never ridden a cruiser of any type and got excited to finally try one out.
I have to say I had a lot of fun. Made the day feel like a real vacation: cruising at a less than break neck pace, taking in the scenery, having loads of fun with the torque, and just enjoying the cruiser experience. The bike was sweet. It looked, sounded, and felt just like you'd want/expect a cruiser to.
If you do end up getting a Road King get the one w/o the beach style bars if possible (I think the Classic has normal bars and the Custom has the beach bars, someone correct me if I'm wrong). I was on it for about 6 hours straight through a lot of twisty roads. My wrists were pretty sore from the bend the bars put on them. It got to a point where I didn't want to shift but with all the torque shifting was kept to a minimum.
Second, if you have to or want to wear a helmet bring your own. The helmets at Eaglerider were fugging disgusting!!! I had my choice off a rack and they all had hair, makeup, and all kinds of leftover human head parts in them. Really gross. I went straight to Cycle Gear and bought a RF1000 (I was looking for an excuse anyway but I'd have bought something cheap regardless just to get away from that filthy disease infested piece of garbage I had).
If you are really set on a sport/sportier bike you may want to look to a local BMW dealership. There are a number around that rent bikes.
I'll answer your question directly.....Spotster or Dyna Sport? I would recommend the Dyna. It's the must unsung and underappreciated Harley. I' havent ridden the 2005 Sportster but the Dyna Sport handles(IMHO) as well as the 2004Sporty (which I have ridden)with the Big Twin experience. I own an EGLide but I find short jaunts on my buddies Dyna Sport to be a real hoot.....its significantly lighter and better handling. If youre gonna do 300 mile days,by allmeans get the EGLIDE but if you are gonna just blast around the back roads,go with the Dyna Sport......youll be pleasantly surprised. As far as the standard VROD,I love the motor,but at 5'11"" 220 lbs,I find the ergonomics painful. Its a shame the new VROD isnt available.........go with the Dyna Sport.
To make the biggest impact, get the "Harleyest" of the bikes -- the Heritage Springer. To hell with modern suspension! One look at the whitewalls and the men will want to be you, and the women will want to fondle your fringe.