Autocomplete or Select box? (design problem)

I'm working on a comparison website, so needless to say the search function is the primary feature of the site. I have two input text boxes and a search button. At the moment, the input text boxes use Ajax to query the database and show a drop-down box, but I'm wondering if it would be more intuitive to use a select box instead? The second box is dependant on the first, as when the first is selected theres another ajax query so only the available options for the first selection appear in the second inputs autocomplete box.

Autocomplete

Pros: - "Feels" right? - Looks more appealing than a select box (css design)?

Cons: - the user has to be instructed on how to use the search (made to think?) - Only really works off the bat w开发者_运维技巧ith javascript enabled. - The user may get confused if they type in what they want and no box appears (i.e., no results)

Select Box

Pros: - Can bring up the list of options / know whats available from the outset. - We use select boxes every day (locations etc.) so we're used to how they work. (more intuitive?)

Cons: - Can look a little unaesthetic when theres too many options to choose from. I'm thinking maybe at most around 100 options for my site over time.

Any thoughts on how I could go about this would be appreciated!

You will have 100 unique options? My guess is that those can be classified in some way. You already have one dependency in you form, adding another to produce a dependency chain seems like it would be intuitive. I've seen dependency chains used in a few places and they work well as it helps the user do a step by step restriction of the search space.

I also think that form should follow function, so Pros list for auto complete is weaker if you follow this philosophy. Also, one of your pros is an abstract concept that you couldn't put into words when writing the question, so the list is weaker anyways.

hmmmmmmmmmmm

Select box looks kinda weird, it could be right choice if there are lesser options, but it would be non influential if you had 100's option in it. The thing that user are also not into the habit of seeing something like this could make this thing worse.

On the other hand you can out something like no suggestion or make text box red when no match found.