A little late to this thread but...
When we travel (wife and I both have the Hydros Pro) we use the backpack that came with the BCD, I bring a small duffel that will easily fit under the seat in front of me (and that I could gate check if I had to), and we check one bag. We get free checked bags due to the credit card we have.
Backpack - Carry-on and we put it in the overhead bin. We pack this stuff just in case our suitcase doesn't make it so we'll have a day or two of clothes and our key diving stuff.
- BCD
- Regulator
- Mask
- Dive Computer
- Swimsuit
- Rashguard
- One pair of shorts
- One pair of underwear
- One wicking t-shirt
Small Duffel - Carry on and placed under the seat in front of me (but I could gate-check this bag if I had to after I move the electronics and documents to my backpack). On the way home, I will often just check this transferring the electronics and toiletries to my backpack.
- Toiletries
- Clothes (2nd swimsuit and spare rash guard)
- Documents
- Electronics
Suitcase - Aqualung SCUBA suitcase that I purchased on impulse but has worked out well. I taped over the large "Aqualung" logos on the side which helps me identify my bag and maybe hides the fact it's scuba stuff a bit. I use a TSA lock on the main compartment mainly to prevent it from accidentally opening during transit. It's not going to stop anyone determined.
- Wetsuits (sometimes four of them!)
- Booties
- Fins
- Spare Masks
- Save-a-Dive kit
- Dry bag
- Snorkels
- Insect spray/sunscreen
- More clothes if necessary
We find packing cubes useful in the duffel and the main suitcase as they keep things organized. For example, my electronics can be in a small travel cube and if I need to move them from that duffel to the backpack, I just have to move one thing.
Finally, we generally only have to fly non-stop about 2 - 3 hours to get where we generally go (south Texas to the Caribbean) so it's pretty straightforward.