Want to make a GIS travel platform

Just want to know for general level, how big, how many person is the work about.

Seem the google is not open source, can only load from it. Is it true? Any other platform?

It need to build a map in IE, may people can search hotels on it. Just like google.

So let's set aside for a minute programming the client side of it, which is somewhat trivial compared to the big question -- where is your underlying, street level data going to come from?  What algorithms will you use to find the shortest route?  How will you keep your street level data current?

If you intend to build this from scratch, it is a massive undertaking.  How will you insure that you have sufficient street level data to suggest the best route to a given hotel while allowing the trip to begin from *anywhere*?  Think about that a minute, and appreciate how much data that is...

What is your specific objection to my first suggestion, the Google Maps API?  I'm still unclear on why that's not exactly what you're looking for...

I need mark all the hotels and other things on the map, also can search the hotels by different price. Can google API do it? How to add my data or database or integrate with google map?