While there are many places to put in in between Tigard and West Linn, I like starting from the Tualatin Community Park. It offers the best and easiest boat ramp for loading and unloading, and there are numerous nice restaurants close by to grab a bite to eat after your adventure.
The Tualatin does allow motorized boats. But with a no wake restriction, it leaves few to be seen except for the occasional fisherman. Most all you will find on your visit will be canoes and kayaks, out for a leisurely paddle, trying to escape city life. Even if just for a short while.
For photography, the river offers lots of great shots. There are many old docks along the banks and the mornings often bring a beautiful mist that likes to hang over the water.
Also, try to go on a day with little or no wind. It makes shooting photos really hard when your kayak or canoe is being blown around messing up your composition. Patience is key to get the shot just right.
If you get really adventurous, park a second car at Willamette Park where the Tualatin meets the Willamette River. From the Tualatin, Park it will take about 2 to 3 hours of nice easy paddling and you'll cover about 7 miles.
Along the way you will pass under I5 and I205 and cross over a small dam. Once over the dam you will find some fun on and off again white water that is super easy and just big enough to get you a little wet and keep you on you toes.
Once at Willamette park, you can load up and head back, or play around a little on the big river before heading out. Either way, you'r sure to have a good time and be amazed that you had never paddled there before.