Hey JC welcome! I personally have found that its better to begin with smaller semps, (not talking variety but age of plant. If you are getting a large plant, it is probably more than a year old and may bloom out)
Last year I bought several that were already larger because I wanted to see how big they'd get! They did get large and it was great looking, but they bloomed, and therefor died (the blooms were amazing, and since they aren't very expensive individually, I considered them to be my "annuals" for that year)
Ones that I've heard of or seen or grown that are large
'Red Lion'
'Fame' (or Fame Montrose)
'Sanford's hybrid'
'Silver King' (the red and green bicolor one, I've seen 2 plants that look totally different, both called Silver King, but the one I had which grew to a 9inch rosette!! was green and red and smooth, rather than fuzzy)
Can't wait to see photos if you decide to share some!! Most of us get a kick out of seeing what others are doing with their semps!!