If a certified meeting planner isn't in your budget, contact the local convention and visitors bureau. In most cases they can put out an inquiry to all hotels in the area that meet your specs and consolidate the responses for you -- and this is often a free service.

As has been suggested by a few members up-thread, when doing block bookings of your size, various other hotel service items are up for negotiation. Look at it as a whole package. For example if your group also needs meeting rooms, and F & B (food and beverage services during or just before or after the meetings) then that can be tied up into a package with the number of sleeping rooms your group will guarantee.

Just one example, if the hotel is offering a high rate for meeting room rentals, use either or both of the guaranteed number of sleeping rooms and hotel food and beverage services to waive or reduce meeting room rentals. Hotels will usually want to negotiate a written contract for this sized group and that protects your group's interests as well. Another tip is to ensure that if your group uses meeting rooms at the same property, that you have an immediately responsive, empowered single point of hotel contact if anything goes amiss, esp. during the time your group is meeting.

For all the above reasons, I, too, recommend using a skilled meeting planner who has negotiated these deals with hotels, given the size of your group and any meeting and F & B uses it may have. If all your group needs is sleeping rooms, then there are negotiation issues available such as room rates, frequent guest credits, parking and wi-fi charges, included breakfast, etc.

OP - What exactly are you planning? It makes a huge difference:

1. Is this a business event where you (or your employer) are picking up the tab for rooms, food, transportation and the like? If so, are these employees, customers, and what are their expectations? E.g., does an open bar mean single malt or swill?

2, Is this personal such as a wedding?

All of this means that you have to look at who pays for what. Do you care about a room discount, if the food is included? Is there a guarantee which you must meet whether the guests show up or not?

Above all, understand that this is a business transaction. If it isn't in the contract which you will sign, it isn't part of the deal. Those sodas during a break can cost $3-7 each depending on location. Extension cords cost money. Who pays for wifi?

Everything costs and everything is a negotiation. It is a 100% guarantee that if you don't do this stuff regularly, you will miss something and it will cost more later.