If you park at the trailhead directly beneath Latah Jct, be aware that it's occasionally the scene of break-ins. Plenty of places to walk and climb to from there. The dirt lot on the south side of W Sunset Blvd just across from S Hemlock is a safe and legit spot, as are the various surface streets near there. Well, the safe part might be in question depending on which exact street and the time of day (or night). I'll second that recommendation about S Coeur d'Alene Street; take it north and then northwest and you'll find a couple of bluff-edge viewing spots. On the city's South Hill, hook over to the west end of W 9th Ave and it dead-ends where there's some good viewing that overlooks the east end of Empire siding. Last but not least, the South Garden Springs Rd bridge that spans I-90 way up on the Sunset Hill offers a nice late-afternoon/evening view down on the city and the bridge, though it's gotten very treed in on the left over the years. That long lens you've been using around Helena will love it.