Jordon provided you some excellent insight on the different calendar tools available. Most companies can get by just fine with these solutions.
Keep in mind that selecting the wrong tool could make things more difficult for your employees. The last thing you want to do is waste time and money on product that only provides little value. There are a couple more questions you should ask yourself before selecting a calendar for your company.
What features are most important for my business?
Which solution will still be a valuable tool as my company grows?
If you don't like the answers to these questions, then you might be looking to have a custom built solution. The beauty of going with a custom developed solution is that you get exactly what your looking for and it can easily be upgraded as you company grows.
Feel free to give Jordon or myself a call at Insivia. If you can give us a few more details, we can help steer you in the right direction.
Good Luck
Eric Purcell
Products & Partnerships Advisor
Insivia
www.insivia.com