Hi Richard -
I don't use booking apps on my site, either.
Like Katia, I use deep links; and to a lesser extent, search boxes. My best results come from the deep links to specific hotel pages on the affiliate company's site. For some reason, search boxes and banners don't convert at all well with my audience.
For airline bookings, I have a Priceline search box on a few pages of my site. In the last 3 or 4 years, I think I've sold two airline tickets. Suffice to say, airline bookings are not a big earner for me.
For hotel booking affiliates, I primarily use Trip Advisor. I've tried HotelsCombined and Priceline, but I've never made much with them. That's probably because HC and PL only pay a commission for a completed hotel booking. And I get very few of those.
Over the years, I've learned that visitors to Cape Cod are more likely to book their stays directly with the hotel, rather than through one of the big booking sites. I'm guessing that's because most hotels in our area are small and locally owned, and you can usually find a better rate on the hotel's website or by calling the hotel than you'll find on the big booking sites.
The reason TA works better for me is because they pay commissions for what they call "commerce clicks" - when a visitor I've sent to TA's site clicks a link on TA's site. No need for the visitor to actually book a hotel and complete a stay for me to earn a commission. As long as one of my site visitors clicks around on TA's site, I'll earn something from the commerce clicks.
The commission on a commerce click is small-ish (usually under a dollar per click), but they do add up nicely over the course of a year.
BTW: If you're looking for an affiliate program for vacation rentals, HomeAway and VRBO have a really sweet commission structure! And they appear to have a bunch of nice rental listings in your area. https://www.homeaway.com/results/georgi ... inSleeps/2
Sorry I couldn't be of any help with your question about apps. I hope the info above is of some benefit for you!
Edited to add this P.S.: I noticed that your site's copyright info is out of date. It still says 2009.