Can't imagine this is relevant to a lot of folks here, but corporate event audio visual:

Don't use the audio visual company that's "in house" at a hotel. They're paying nearly 50% commission for the privilege of being there and getting business shunted to them, so only half of what you pay is going to goods or services.

That said, make sure your hotel contract leaves you free to bring in an outside vendor without having to pay too many fees. Cross out any lines related to things like "load in/out liaison," paying for polytak floor covering, or paying some percentage of your outside AV bill to the in house company. It might help to include a proactive clause like "client will not be charged any fees for bringing in our own audio visual partner". Include a line that you won't be required to pay surcharges like "event technical support" which is just a "we're charging you a fee" fee.

You will still have to pay the in-house AV vendor for any power, internet and rigging. For internet, confirm what your rate will be before signing the contract. We see a lot of cases where they'll say "the meeting room wifi is discounted (free) if you use us for AV too, but if you don't it's $20k" (actual number, and could be even higher) Once you sign without negotiating they've got you over a barrel.

If you already have a contract you may be able to mitigate these issues by leaning on your hotel salesperson. Trying to negotiate with the in house AV rep will usually be ineffective (sometimes they're cool). The hotel is the in-house AV vendor's number one customer, so if the hotel says they need to do something, they'll do it. Usually leaning on your hotel salesperson after signing a contract only works if you have some leverage like potential for future business.