2. Putting in a day is a long commitment (so as byoung says, you should offer #1 for free and no signup, and make a convincing case for using #2. The benefit is having a centralized control panel for multiple different social media sites with different interfaces and tedious junk.
Make sure to generate an email address so that all the resulting welcome/membership/spam emails go through your clean and professional tool rather than cluttering up the user's inbox. And don't let them use it to spam HN, of course :-)
I would do graduated pricing. $25-$50 for a week of promo, which should be long enough to get some analytics traffic (did I mention it auto-signs-up for analytics?). $100-250 for a month, $1000+ for a longer campaign. Lower prices limit you to 5, 10 or 20 outlets and 3-4 updates over a week, higher let you do more frequent or structured updates.
I can see some definite potential for this. Lots of businesses want to do internet PR but don't want to devote major amounts of time to it. The multiple different interfaces and signups are the biggest time killer - if you can perform essentially similar or related functions in many different contexts and give a clean top-level action/report interface, it'll be a winner. Just make sure the starting price is cheap enough for people to get their feet wet, ie no bigger than a petty cash expense and a few hours of work. Once they see that pay off in terms of gaining eyeballs, they'll be hooked.