1) You've GOT to have a stroller. Even just on Alcatraz Island, I don't know how you would walk around (successfully) with an 18-month old. There's a fairly steep hill from the boat to the main building.

2) Are you looking for a fancy hotel or a roadside motel? Your best bet might be one of the motels on Lombard Street. They're not fancy, but many are very decent, and Lombard St. runs parallel to two shopping/eating neighborhood streets - Chestnut to the north and Union Street to the south ---- easy walking distance. We also had cousins who stayed with their kids at the Holiday Inn Express at FW and they were perfectly satisfied.

3) Whether your budget is sufficient depends on the time of year you're coming to SF. You won't get a fancy hotel for that price, but you'll get decent accommodations, and better in winter than in summer.

Thanks. We will bring a stroller then and also our backpack carrier.
We are not looking for fancy, just somewhere to lay our heads at night where we can have a good nights sleep. Clean and a comfy bed are all that's needed really.
We are coming in April.
I will look into Lombard street thank you

Can you recommend some good ones on Lombard st?

Check out the Chelsea Motor Inn (and her sister properties)on Lombard. I have stayed there twice. Nothing fancy, but clean and comfortable.

http://www.chelseamotorinn.com/

The Chelsea hotel group is often recommended. They look nice, and again, the area is very convenient.

April is often busy here, so do make advance reservations for Alcatraz. There's only one official boat, and only one way to get to on the island - everyone else selling tickets is "after-market" - they may be including more than just Alcatraz, and may also be over-charging.

http://www.nps.gov/alca/index.htm

You might also look at the Columbus Motor Inn--it's near the Wharf and would be convenient for where to have to go.

Thanks have been looking at Columbus so good to know that would work, will look at Chelsea group too and as soon as booked I will book Alcatraz.many thanks all.