Ssl certificates for *.subdomain.example.com

The main limitation is that with one ip address you can have one ssl certificate.

Since you only want ssl on the blog then there's no problem with the setup you've proposed, just make it the only virtualhost listening on 443

# Virtualhosts on ports 80 and 443
NameVirtualHost *:80
NameVirtualHost *:443

# rewrite blog traffic to https
<VirtualHost *:80>
        ServerName blog.example.com
        DocumentRoot /var/www/blog
        RewriteEngine On 
        RewriteRule ^(.*)$ https://blog.example.com/$1 [R,L]
</VirtualHost>

<VirtualHost *:443>
        SSLEngine on
        SSLCertificateFile /etc/apache2/ssl/server.crt
        SSLCertificateKeyFile /etc/apache2/ssl/server.key    
        ServerName blog.example.com
        DocumentRoot /var/www/blog
</VirtualHost>

<VirtualHost *:80>
        ServerName othersite.example.com
        DocumentRoot /var/www/other/
</VirtualHost>

The slight limitation here, is that the blog will catch all https traffic here, regardless of hostname, so https://othersite.example.com will point to the blog, and generate errors because the name doesn't match the certificate, but there's no way around that with one ip address.

First, SAN certificate = UCC certificates. They are both just certificates with the SubjectAltName field.

Second, a wildcard of ..domain.com won't work in most browsers. You will either need to get two wildcard certificates (one for *.sandbox.domain.com and one for *.domain.com) or get a wildcard certificate for *.domain.com and have your SSL provider put a specific SubjectAltName of ja.sandbox.domain.com. I think DigiCert and GlobalSign offer this.