I just happened to run into the same or similar issues recently when attempting to fully automate differing un-attended system builds with ubuntu 14.04 on amd64

I was able to make the provided -atomic and -home recipes work, but they don't offer any control over the sizing of the logical volumes.
The -multi recipe doesn't work.

The expert-recipes don't work either, no matter what I specified, the end was result was the same, I'd get a /root a /swap_1 logical volume and  /boot partition, and never close to the sizes specified, nor the filesystem type specified, nor the logical volume name specified :-)  

Below are the options and recipe used.
I was about to try using kickstart versus preseed to try and setup LVM on ubuntu how I want. On my rhel/centos systems customizing LVM is a breeze with kickstart automation

### Partitioning
d-i partman-auto/disk string /dev/sda
d-i partman-auto/method string lvm
d-i partman-lvm/device_remove_lvm boolean true
d-i partman-md/device_remove_md boolean true
d-i partman-lvm/confirm boolean true
d-i partman-lvm/confirm_nooverwrite boolean true
# You can choose one of the three predefined partitioning recipes:
# - atomic: all files in one partition
# - home:   separate /home partition
# - multi:  separate /home, /var, and /tmp partitions
#d-i partman-auto/choose_recipe select atomic
#d-i partman-auto/choose_recipe select expert-recipe
# Give the default VG a name 
d-i partman-auto-lvm/new_vg_name string vg
d-i partman-auto/purge_lvm_from_device boolean true
d-i partman-auto-lvm/guided_size string 90%
d-i partman-partitioning/confirm_write_new_label boolean true
d-i partman/choose_partition select finish
d-i partman/confirm boolean true
d-i partman/confirm_nooverwrite boolean true
d-i partman-md/confirm boolean true
d-i partman-partitioning/confirm_write_new_label boolean true
d-i partman/choose_partition select finish
d-i partman/confirm boolean true
d-i partman/confirm_nooverwrite boolean true
####
# Experimental disk recipe
#####
d-i partman-auto/expert_recipe string
  custom-lvm ::                                               \
              40 300 300 ext4                                 \
                      $primary{ }                             \
                      $bootable{ }                            \
                      method{ format } format{ }              \
                      use_filesystem{ } filesystem{ ext4 }    \
                      mountpoint{ /boot }                     \
              .                                               \
              2000 4000 10000 ext4                      \
                      $lvmok{ } lv_name{lv_root}             \
                      method{ format } format{ }              \
                      use_filesystem{ } filesystem{ ext4 }    \
                      mountpoint{ / }                         \
              .                                               \
              2000 1000 2000 ext4                            \
                      $lvmok{ } lv_name{lv_var}            \
                      method{ format } format{ }              \
                      use_filesystem{ } filesystem{ ext4 }    \
                      mountpoint{ /var }                      \
              .                                               \
              2000 1000 2000 ext4                            \
                      $lvmok{ } lv_name{lv_home}             \
                      method{ format } format{ }              \
                      use_filesystem{ } filesystem{ ext4 }    \
                      mountpoint{ /home }                      \
              .                                               \
              512 512 512 linux-swap                       \
                      $lvmok{ }  lv_name{lv_swap}           \
                      method{ swap } format{ }              \
              .