I\'m curious about whether the approach of using multiple strongly typed partials within a form that posts back to the partial containing View is the right MVC approach to doing
This is because your Partial views are strongly typed. Remove the @model declaration in your Partials and access the Model properties like this
@Html.Partial("_LoginAccount")
and then in your partial
<div>
@Html.TextBoxFor(mod => mod.UserLogin.LoginId)
@Html.PasswordFor(mod => mod.UserLogin.Password)
</div>
All partials views should be strongly typed with the same view model (AccountSetup in your case) :
@model Models.Account.AccountSetup
@Html.TextBoxFor(mod => mod.UserLogin.LoginId)
@Html.PasswordFor(mod => mod.UserLogin.Password)
Then:
@Html.Partial("_LoginAccount", Model)