Flickr is quite good for sharing of full resolution photos. They can download at full resolution, print themselves, or even order prints depending on how you set the permissions. (You'd have to invite the other parents to become contacts in order for them to have permission to order prints).
Yes, it's free for a certain amount of storage -- but the free storage is HUGE. I have like 6000 photos, that are about 10mb each.... And I'm only using about 1% of the free space. You can pay extra for an "ad free" account.
From their FAQ
What’s the difference between a Free and Ad Free account?
Free:
1 Terabyte of photo and video storage
Upload photos of up to 200MB per photo
Upload 1080p HD videos of up to 1GB each
Video playback of up to 3 minutes each
Upload and download in full original quality
Unlimited monthly bandwidth
What's a Terabyte?
Short answer: 1 trillion bytes.
What’s a byte, you ask? All right, we’ll bite. A byte is a teensy unit of measurement for digital information, usually containing 8 bits. (One byte generally contains enough information for a single character on a computer.) Even though one byte is itty-bitty, a trillion bytes is a whole lotta space -- that's over 500,000 photos to share and enjoy in their original, brilliant quality. Snap away!