Skip the Thumb
Most people who hike Tom's Thumb trail from the North side are planning to visit its namesake "the Thumb". If you're looking for a different view then this is the hike for you. I enjoy Tom's Thumb north for it's steep climb and good workout combined with beautiful granite boulder field and incredible views along the ridge in all directions.
Follow the signs from the trailhead parking lot for Tom's Thumb trail about 1.6 miles to junction with East End trail. Stay on Tom's Thumb for another 0.5 miles to the sign for The Lookout trail. Go left (south) 0.5 miles to the dead end Lookout and look down and all around you. Windgate Pass is below and Thompson Peak not too far away. Behind you is the classic Thumb and East End Peak.
Return the way you came - or if you just can't resist stopping by the Thumb - then watch for a sign that says "Rock Climbing Access Route: Tom's Thumb/Gardener's Wall" about 0.1 miles from the junction with The Lookout. Taking that out/back section to the base of the Thumb adds 0.8 miles to your roundtrip total.
The trailhead has equestrian parking, two regular parking lots, info plaques, maps, non-flushing bathrooms but NO WATER!
Check out the Official Route and Triplogs.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.