Non-HDR apps, for taking family pictures or photos where there is motion present, are also abundant. Among those I like are the already mentioned built-in camera controls from Apple. I'm also a fan of the popular free Instagram app that provides camera control and a variety of editing options and filters, and Camera + which is both very popular and a well performing $1.99 app. It contains granular camera control, and a host of features for both taking and editing photos.
Let's not forget panoramas. Apple added a very good panorama feature in iOS 6, and it works great. (You need an iPhone 4S or iPhone 5.) Put the camera in Panorama mode, and slowly move it from side to side while the camera captures and instantly assembles a high-resolution horizontal image.
There are hundreds of apps that let you edit photos. Fotor and Camera + do a nice job, and both have a variety of filters if you want to apply them to your photos. I think the standout app is the free Snapseed app. It has an easy to use GUI, and best of all gives you a tremendous amount of control over several parameters that can make your images compelling. Even if Snapseed had a price tag associated with, it would still be my recommendation -- being free, it is a terrific choice. Apple's camera app does have some on-board tools like cropping and simple enhancing, but Snapseed is far superior.
I also like to create collages and send them to friends while I am still traveling. My favorites in this area are Diptic ($0.99) and ProCollage ($1.99).
You're on your trip, and want to share those photos before you get home. Again, there are plenty of options, including services like Flickr, Amazon Cloud Drive and Instagram, but I really like the free app Photoset. This universal app lets you select photos, upload them to a website, and send the url to friends. You don't need to sign up to anything, the photos look great, and unlike Apple's PhotoStream option, the pictures will never go away. My only wish for Photoset is that you could select multiple photos instead of selecting them one at a time before uploading.
Where and When to take pictures
Just like in real estate, location is everything. Sometimes you are taking pictures wherever you happen to be, while others look for the best places to visit specifically for photography. If you are in the US National Parks, the Chimani guides are indispensable. This series of free apps provides information like hours of operation, best photo spots, and travel tips for the major National Parks.
The time of day that you take that picture is really important too, with the best lighting occurring during the so-called "golden time" just before sunrise and just before sunset. Magic Hour is just the ticket for figuring out the best time to take those wonderful pix. The app is free, uses GPS to figure out where you are, and then tells you the best time to grab those beautiful landscape photos.
How about figuring out the best nearby photo locations? If you have an iPad, grab the free Stuck on Earth app. It shows your current location on a map, and scours the web for photos taken at that location. It gives you a great idea about what to expect and is also handy for trip planning before you ever leave on your vacation. Sadly, this app is not available for the iPhone, and there isn't an iPhone app that is comparable.
The apps mentioned here will go a long way toward making your vacation photos memorable and worth sharing. I still am amazed that such great technology can be stuffed in a smartphone, but there it is. Have a safe trip, and may you get lots of great photos.