A great first dive is Oil Slick Leap. You don't have to walk in, just gear up and jump in or climb down a very nice ladder. To exit just come back up the ladder. Since there are two of you, one can help hold cameras, gear etc. The "leap" will probably seem higher than it is. To see someone doing a entry - I've include a link at the bottom with times for various scenes.
As already mentioned, the old Witches Hut (now Weber's Joy) is a great dive and quite easy entry. I had done this on a previous trip and enjoyed it as much the second time around.
If you can, do Invisibles and make it out to the second reef. There are so many interesting things on that dive. You will see garden eels on the way out. A good chance of seeing eagle rays on the way out. There always seems to be a mini-bait ball with bigger fish always around. We found a frog fish on that dive. I could literally do that dive every day and be happy. Shore entry is pretty decent and you can park very, very close.
If you are comfortable with a bit bumpy (but very quick) ride, drive over to the wildside for a few dives. In just one dive, I stopped counting turtles after 15! Two divers saw dolphins, yeah pretty awesome.
Our trip video from February 2011 (Should Be IPad / iOS friendly)
http://www.amazonbeach.com/films/samples/Bonaire2011_001_H264_1024x576_2997fps_4Mbps.mp4
Time 11:00 - Oil slick leap scene starts at time 11:00 with jump in about 30 seconds later. You will see the ladder, someone exiting and some entering.
Time 12:50 - A Frog Fish extending its lure! This was actually at Invisibles but I cut it this way to be different.
Time 19:00 - The ever present mini-bait ball and bigger critters at Invisibles.
Time 20:10 - See what its like to ride out and dive the Wildside!